the state department sent a few hours ago to the u.n. makes very little sense. that's it for this season of "on assignment." we're grateful to rachel for lending us her fridays. we'll be back in a few months with more stories from other parts of the world. president trump's asia trip has been all about trying to push north korea. the question is, what is kim jong-un going to do next? will he give up his nuclear ambitions or will he push back? it's the most dangerous conflict in the world and i recently got right up to the front lines in the cockpit of an f-16. >> so this is about the north edge of the air space. we're about seven miles from the north korean border right here. >> so this is as far as you can go without provoking a war? >> yep.

president trump is in da na nang, vietnam, today as part of his continuing trip to asia. he spoke this morning to business executives at the asia pacific economic cooperation summit. he told the ceos that the united states has not been treated fairly in international trade. but now the president said the u.s. will set trade policy under the guideline of america first. so far in asia, president trump has been getting fairly positive reviews. he's looked presidential and he didn't, despite some early concerns, trigger a trade war with china or a nuclear war with north korea. i spoke earlier with a source who has direct knowledge of the details of the trip. he told me that the president's advisers worked hard to tone down the speech he made here in south korea. but i don't think we're out of the woods yet, not by a long shot. in fact, if you listen to what our president said, it's clear we're on a collision course with the regime. and that's enormously dangerous. the president said repeatedly and in the strongest terms possible, that north korea must

disarm. that it must stop developing nuclear weapons or face military consequences. he said every step north korea takes to advance its nuclear weapons makes the regime less safe. but north korea shows no sign of disarming. so this has become a game of chicken over weapons of mass destruction. we have been down this road before. but this time, the consequences are more serious than anything, most, if any, of us have ever experienced. we're talking about the possibility of a nuclear war in our lifetime, or at least, of a conventional war that could spread across asia. what are the chances of this actually happening? well, a retired four-star general told me he thinks there's a 51% chance of war with north korea before next summer. even if that's too high, even if it's 10%, the risk is not zero. no way. and if this does break out, this city is in big trouble, because right now, all the time, in fact, north korea has thousands of rockets and artillery pieces

pointed here. if the north korean regime feels threatened, if it feels it's being driven from power, it can, and military experts say it probably would destroy seoul. and the south koreans, the 25 million people living in this city, can't do much about it. they're stuck between kim jong-un and one side, who's determined to have a nuclear weapon program, and president trump, who wants to take it away. you can imagine how it makes people pretty nervous here, especially this week, when president trump arrived in asia with an armada, and while the military here is in high gear. >> ninja 2, verify. >> here at osan, they've been preparing for war for more than six decades. >> this is the closest air base to north korea, so if war breaks out, it will be both a key launch pad for american firepower and an obvious target

for incoming fire from the north. i joined captain kyle moses, aka, the beast. >> climb up the ladder. >> all right. >> on a mission to one of the most dangerous spots on the planet. >> watch your elbows. canopy is coming down. >> the demilitarized zone that separates north and south korea. the north koreans have been threatening to shoot u.s. planes out of the sky, so even a routine mission is dangerous now. >> ground check one. cleared for take off. visor down. seat is armed. here we go. >> and it doesn't take long for captain moses to demonstrate why they call him the beast. >> all right, get ready for some "g" here. >> after takeoff, he puts us straight into a roll. the plane takes on up to nine times the force of gravity, or nine g. >> how's that? >> that was intense.

>> yeah. >> as we reach the front lines, captain moses positions his f-16 very carefully. >> so this is about the north edge of the air space, we're about seven miles from the north korean border right here. >> so this is as far as you can go without provoking a war? >> yep. >> now, can we look into north korea? >> oh, yeah. over those mountains there, you can see into north korea there. >> so is that where all their artillery is and all those rockets? >> oh, yeah. >> if you were called into aggressive action, would that be possibly a target? >> yes, that could definitely be something we could go after. >> we head back to osan. another routine patrol ending, thankfully, without incident. the pace here is relentless. captain moses's 36 squadron flies f-16s, but the base is also home modernized u-2 planes

on 12-hour flights at high altitude, keeping a constant watch on the enemy to the north. for months now, the u.s. military has been quietly beefing up its presence in the region, and we've been following every step. in august, joint drills with the south koreans suddenly took on a whole new urgency. the enemy is left unnamed, but it's clear which battle they're rehearsing for. in september, we watched as american troops moved a battery of thad missiles, the most advanced missile intercepters in the world into position. >> missile defense systems aren't just about defense. they give those who have them the ability to attack and survive a counterattack. and while the thad has not yet been used against real incoming missiles, it adds another layer of protection to the extensive missile defense system already in place. then, just a couple of weeks ago, what the president called an armada arrived in the

peninsula. three aircraft carrier strike groups, capable of sustaining a prolonged air campaign. military experts believe all this hardware is not just here for show. >> we're actually dealing with potential outcomes by next summer of all-out war. with millions displaced and hundreds of thousands killed and wounded. >> retired four-star general, barry mccaffrey, is a dead rated veteran of war. he says that in the case of north korea, there are no good options. >> there are military options. they're all bad. if we went in with a massive vn conventional air and sea attack aimed at their nuclear capacity, eget 95% of it in the first 72 hours. but we wouldn't get all of it. or we wouldn't be sure. and that would probably trigger a very high-intensity conflict in the korean peninsula. the consequences of us attacking

north korea first would be dire. >> but the alternative to military action, known in washington as strategic patience, has become for the president, a symbol of all the mistakes of the past. >>t the era of strategic patiene is over. >> a view echoed by some of the president's backers. >> patience is not an option with the u.s. homeland in the nuclear shadow of kim jong-un. >> senator cory gardner, a republican from colorado, says strategic patience is just another name for do-nothing approach. >> if your kids are at the table and they're throwing food around at each other, do you just sit back and say, i'm going to strategically wait until they fight -- >> but this isn't a food fight. this is something far more serious. >> what we get with patience is a nuclear program in north korea. what we got with patience is a launching of ballistic missiles. >> but we also got to all survive. we also are here. there is still a korean peninsula. >> well, if you trust -- if people believe they can trust

kim jong-un, he said he would use his weapons, i believe him. that's why we have to make sure that he doesn't have that ability. >> and those weapons would likely be used first on our south korean allies. >> most of the enemy forces are located here. 70% of their fires -- >> as defense secretary james mattis was reminded when he recently visited the demilitarized zone. mattis did his best to reassure his hosts. >> our goal is not war, but rather, the complete verifiable and irreversible denuclearization of the korean peninsula. >> it's a tricky message he was trying to deliver, that the u.s. is ready for war with north korea, while trying to avoid it at all costs. it's the same message the military has been trying to send, too. >> i know a lot about the joint chiefs and who they are. they're very responsible, cautious men. this generation all grew up until warfare. old guys never want to fight. >> but while the generals in

universal and in the cabinet have been cautious, the president has, at times, been flat-out threatening. >> north korea best not make anymore threats to the united states. they will be met with fire and fury, like the world has never seen. >> i think the president is more of a new york city hustler. so he's learned some lessons that are not applicable in international relations or international security. >> general mccaffrey is an outspoken critic of the president. >> there's an element of disbelief on the part of many of us who have seen combat at close range, to see him so lightly dealing with these topics. >> the president has made it clear he will continue to evaluate the pressure on north korea, until its leader, kim jong-un, steps back from the brink. the problem is that the 33-year-old north korean leader,

the third in a family dynasty, that has wielded absolute power over the country for nearly 70 years, does not seem to be yielding. he sees his nuclear program as a source of national pride. and the right to keep it as a matter of life and death. so the more our president vows to end it, the more tests kim conducts. senator gardner dismisses the north korean leader as a madman, who needs reining in, by force, if necessary. >> i think most people agree that kim jong-un is a whack job. >> you call him a whack job, they call you a man mixed with human dirt, who has lost basic judgment and body hair. >> he doesn't like my body hair. not sure if that was an onion headline or if it was real. >> but we're not in the schoolyard. the consequences are real and serious. >> they are and that's why we have to ensure we have these tools we must ewe to change the situation. >> president trump said of president kim at the u.n. general assembly, and i quote,

the united states has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy north korea. rocket man is on a suicide mission for himself and for his regime. >> the regime responded by calling our president a deranged dotard. is that really the way two world leaders should be conducting diplomacy over such sensitive issues? >> i would have said something different in front of the united nations, but i think it's very important that we be clear that he's not going to get away with what he had in the past. >> we've got a president of the united states who is publicly taunting and mocking a 33-year-old quisquirrely dictat with a nuclear program. it's an adolescent kind of way of dealing with a problem. why would we ridicule a person that quit so txotic, that volat?

what good could possibly come from that? i imagine that president trump probably has access to cia psychological profiles of kim jong-un and i'm sure it probably says somewhere in that profile, probably in red letters, do not insult this person. >> susan dimaggio uses more diplomatic tones. she's been involved in back-channel negotiations with the north koreans for a couple of years now. >> we're stuck in an escalating war of words. and we have to get out of it. >> do you think that war of words could become a real war? >> absolutely. if it's not managed well, this is how you slide into war. this is how you sleepwalk into war. >> and you think we're sleepwalking into war now? >> i think it's possible. >> her last meeting was in moscow less than a month ago on the shriidelines of a nuclear proliferation conference. and there was no doubt about the message from the envoy? >> she said u.s. nuclear weapons were the only way they saw to safeguard their regime from us. she made it very clear that they

are going to proceed full steam ahead with their nuclear and missile program. >> what would get the north koreans to sit down at table and actually negotiate? >> i think once they feel that they can declare that they have a nuclear balance of power with the united states, then they'll be ready to negotiate. i don't think the u.s. has tried diplomacy with -- in a way that warrants even contemplating a military response at this point. >> but d'maggio is not the one calling the shots. the president is. and during his trip, he delivered a clear threat to the north korean leader. >> do not underestimate us. and do not try us. >> speaking before south korea's national assembly, the president carefully read a pre-prepared speech. there were no casual insults, but he was delivering a deadly

ultimatum. >> the regime has interpreted america's past restraint as weakness. this would be a fatal miscalculation. >> the grave language is appropriate, because any miscalculation here would be fatal, to thousands, maybe millions of people. as the president departed, both americans and south koreans were left wondering, which side was going to blink first? and at what cost? that cost in human life could be astronomical. tom brokaw is going to be on the show a little later to remind us what we're talking about, when we talk about nuclear weapons. but first, when the president landed here in seoul, we went out on the streets to see what kind of welcome he was driving into. traditionally, south koreans have welcomed americans, servicemen and presidents alike, warmly. but things haare changing here.

we found another equally passionate crowd. they were here to tell the american president to go home. >> if kim jong-un or trump decided to make war in korean peninsula, there's nothing we can do. it's crazy thing. >> stay with us. ♪ it's time for the ultimate sleep number week on the only bed that adjusts on both sides to your ideal comfort your sleep number setting. and snoring? does your bed do that?

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welcome back to "on assignment." president trump is used to being a divisive figure and having low approval ratings. but here in south korea, his numbers are especially harsh. only 17% of those asked in a recent poll said they had confidence in him. that's a 71-point drop from obama's standing here.

of course, south koreans don't get a vote on who becomes the president of the united states, but they do have strong opinions on that. opinions they aired the day president trump landed here. when president trump rolled into seoul, crowds lined the streets. many were here to welcome the president with open arms. american flags and a rendition of the "star spangled banner." ♪ oh, say can you see >> traditionally, south koreans have welcomed americans, servicemen and presidents alike, warmly. >> we believe the united states and we love the united states. >> reporter: but things are changing here. just across the street we found another equally passionate crowd. they were here to tell the american president to go home. police officers cordoned off the protesters who tried to surge

forward. president trump is expected to pass by here any minute. the police have just started to push in, trying to keep the protesters back. they don't want them to block the president's path. but things soon calm down again. this was not a violent crowd. you're holding a sign? >> yeah. >> what does it say? >> it says, peace, not war. >> peace, not war. >> yeah. >> su young jun is 29 years old. she's one of the leaders of the protests. >> in here, there are lots of students, university students who doesn't want donald trump visiting korea. >> the divide is striking. those waving the american flags are generally older. those holding up the "no trump, no war" signs tend to be much younger. >> the younger generation here, they're not so interested in

north korea, because they haven't grown up with it in their lives. the older generation remember when it was just korea, or the japanese colonial era, for example. so they have a more direct sense of, there was one country and now we're divided. >> daniel tudor came here as a teacher, but fell in love with south korea. he now runs a chain of bars that serve craft beer. he says for the older generation, there is a sense of unfinished busy with north korea. >> i think probably for that generation, if you are of that age, you might think, well, why don't we just get this done? in my lifetime, i want to see this over. regardless of what happens. >> the memory of the bitter war between north and south defines the korean peninsula in a profound way. no one here disputes the fact that it was a massive influx of u.s. troops that saved south korea from falling into communist hands. for generations, gratitude for that and for the protection that u.s. troops still stationed here 64 years after the end of the

fighting define this country. not anymore. by nightfall, the number of anti-trump protesters swelled. su young and her fellow protestors had watched the president's speech on their phones. this is, after all, south korea, everything here is streamed live. [ chanting: usa ] >> on the pro-american side of the street, the feeling was that, if anything, the president should have gone further. >> we strongly demand, request mr. donald trump, please, strike north korea right now. he's thinking about our casualty, but i want to say to him, don't worry, please don't worry for koreans. we are ready to sacrifice our life. >> j.t.'s son was a lieutenant colonel in the south korean army. his stance is stoic and simple.

better dead than red. >> so you're willing to accept the huge costs that -- >> the sacrifice. i may die. which will be fine. just kill the north korean kim jong-un. >> the feeling across the other side of the street was entirely different. why is he allowed to speak in our parliament, shouted su young. no trump, no war. by day su young works as a pharmacist. in korea, it takes four years of medical school on top of a good college education to qualify for the job. she's worked hard to get here. but when we sat down to talk, she sounded downbeat about her future. >> we can't think about our future. think about it. if there's a -- we keep our money or we keep our job or we do lots of things for our future, we study hard, but eventually, if there is a war

happen, it's no -- it's nothing. >> it all goes away. >> we can't imagine our future. >> it's a historical irony that the younger generations here that grew up in modern seoul, one of the richest cities in asia, are bitter about their future. >> i think we lost our own independent power at the global table. >> how does that feel? >> >> if kim jong-un or trump decided to make war in korean peninsula, there is nothing we can do. it's a crazy thing. >> it's not something that you'd think about in day-to-day. but, yeah, you know it's always there. >> they feel like the shadow of death is hanging over them? >> >> if it really happens, i'll be dead in five minutes, so it's better to not think about it. >> when su young and her friends go out, they don't talk about politics or war, they talk about friends and plans and work. do you prepare for potential conflict? >> actually, i don't.

because if there's a war, it's going to be a minute or two minutes that i have to -- there's no option to be alive. it's like we just live only today. >> live in the moment. >> no tomorrow for us. we only have this moment. >> so when i go out in the street and i see the places happy and buzzing -- >> yeah, that's why. we always having concert and go to movies or love each other, but we only concerned about today. that's why. because we're not sure about tomorrow. >> one thing everyone we talked to agreed on is that there may be two koreas, but one people. they long for the day when they can be reunited with their neighbors and relatives on the other side of the border. but the people of north korea

don't get a vote. only their leader does, kim jong-un. so next, we try to figure out what he is all about. and why his regime's pursuit of nuclear power may not be as foolish as it sounds. it's easy to dismiss the regime as a caricature, the bad guys in the teen america movie. >> i don't have any weapons of mass destruction, okay? >> but it's worth lacking past the bizarre cultive personality and the boos-stepping troops and try to actually understand what the north korean leader, kim jong-un might be thinking. stay with us. [vo] progress is an unstoppable force. the season of audi sales event is here. audi will cover your first month's lease payment on select models during the season of audi sales event.

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it's a sunny saturday here in seoul, south korea, and behind me is the city's ancient southern gate. it's easy to forget on such a lovely day that the front line with north korea is only 35 miles away. reporters don't often get access into north korea and when we do, our movements are very restricted. so a lot of the time the only images we get out of pyongyang are pure over-the-top propaganda. we are intrigued by the bizarre displays, by the cultive personality. but there may actually be some logic behind the strategy that's kept one family in charge there for 70 years. when you look at the propaganda coming out of north korea, like this 74-year-old tv announcer who has been there at the desk through all the historic

moments. and now regularly returns to deliver the news of new missile launches or of people filled with awe and emotion at the mere sight of their beloved leader. it's easy to dismiss the regime as a caricature. the bad guys in the "team america" movie. >> i don't have any weapons of mass destruction, okay, has? >> but it's worth looking past the bizarre personality and the goose-stepping troop and what kim jong-un might be thinking. it's also worth taking a look at our own history and asking why we would expect north korea to trust us and come in out of the cold. for years, the north koreans have been working relentlessly to develop their nuclear program, refusing to back down, no matter how loudly they were trend. >> once again, north korea has defied the will of the international community and the international community will respond. >> they will pay a price so great that the nation would

probably not survive, as it is known today. >> the north koreans just kept on going, ignoring both the american threats and the hardships that the sanctions imposed on the people. why? well, it's worth remembering what happened in libya. in 2003, the leader of libya agreed to give up that country's biological and chemical stockpiles to the west and abandon its nuclear program before having a bomb. >> leaders who abandon the pursuit of chemical, biological, and nuclear weapons and the means to deliver them, will find an open path to better relations with the united states and other free nations. >> but only eight years later, libya found itself on a far different path. the u.s. and nato engaged in a bombing campaign to overthrow the dictator, moammar gadhafi. in response, north korean's foreign ministry came out suggesting that the libyans had been duped into abandoning their

nuclear weapons in exchange for a deal with the west. a deal the west did not keep. and more recently, north korea's observing how the iranians came to the table. how they signed a deal with the united states and european nations and almost two years after the deal was signed, we are pulling out. so why would the north koreans fall for what they believe is an american trap? why would they take our president's invitation to come to the table, as anything but a trick? experts argue that north korea's nuclear ambitions, its constant testing of missiles is an insurance policy, a way to make sure that kim jong-un stays in power. a way to make sure that the kim dynasty goes on forever. why is it important to understand what's going on inside the head of the north korean leader? because as president trump himself has repeatedly stressed this week, there are only two places this crisis can lead. the negotiating table or the battlefield. it's hard to imagine a nuclear war breaking out in the 21st

century. but then again, nuclear war is always too horrific to imagine. next up, tom brokaw asks if we're heading for a new nuclear age. with all the friendsgivings and fa la la family dinners, the hustle and bustle of holiday party season is officially on. hi. (laugh) hi! yes! come on in! so serve up some marie callender's dutch apple pie. made with fresh fuji apples in a made-from-scratch crust and topped with sweet crumbly streusel. look at you, dessert duty, judy! you just gave yourself the gift

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welcome back. the president says that north korea went ahead and developed nuclear weapons because previous american administrations were not determined enough to stop it. but the big question now is which side is bluffing? will the president go to war with a nuclear-armed north

korea? or will kim jong-un fire first? the third option that one of them will back down is the only one that avoids an all-out war. so the fact the that nuclear war is a possible outcome of this crisis. that idea, which was completely unthinkable just a few months ago, is hard to take in. so for some perspective, i turned to the man who hired me many years ago to work at nbc news, the legendary tom brokaw. >> august 6th, 1945, 8:15 a.m.. >> when the united states dropped little boy on hiroshima, japan, the first atomic bomb used in warfare, and fat man three days later on nagasaki, it was the beginning of the nuclear age. an age of such potential destruction it could end life on earth. our principle enemy, the soviet union, soon had its own nuclear

arsenal. and i was one of the american schoolchildren diving under desks in a foolish belief that we could survive a russian attack. as a political science student, i was immersed in the great issue and debates of my generation. with the united states and kremlin rivalry lead to a war end to all wars? a 1954 nbc documentary ominously titled "three, two, one, zero ♪ w was prime-time viewing. the idea that the world would end was not an apocalyptic uncertainty. but for all the fear, no one dared to go nuclear. an uneasy truce settled across the world. not peace, exactly, but a kind of standoff between the cold war superpowers. it was summed up in the phrase mutually assured destruction. if either side started a war, both would disappear.

but for other countries, the temptation to be part of a nuclear club was too great and in an age of suicide bombers and unstable despots, the idea of mutually assured destruction may no longer keep the handcuffs on. following world war ii, as the nuclear age was getting underway, the united states was involved in a war in korea, although they called it a police action. 64 years ago, there was a cease-fire. the korean peninsula was divided between the north and the south. no one could have known then that today, north korea would be a major and dangerous nuclear power. nuclear weapons have spread across the world. large nations and small. china and europe, israel, but also pakistan, india, and of course, north korea. a bizarre renegade nation led by

a megalomegalo maniacal dictato plays by no rules except his own. he has developed a sophisticated nuclear delivery system. will he use it? david wright is with the union of concerned scientists, a group of experts dedicated to monitoring the perils of the nuclear age. >> i started watching the missile program of north korea back in the early '90s. i've been trying to get people to pay attention since then and to really put a lid on it. >> what caused all of this proliferation? how did that happen? >> other countries start to think, well, what do we need? what are the threats out there, and what can we do about them? and that urge is very strong. >> what worries wright and his fellow scientist that is with all of these nukes, what about an accidental launch? >> the president of the united states has sole authority to order the launch of nuclear weapons. and nobody in the command system can legally stop that. >> it is not just president trump. how do we develop a fail-safe system so that no one person has

that authority anywhere? if that nuclear chain begins to go off, no schoolboy desks will be much help in protecting millions of people. >> this is one of those surreal moments we get a lot of in seoul these days. tom was just laying out the dangers of nuclear warfare. and behind me are dancers in traditional clothing. they've come out for a daily ceremony. and they seem to have an audience. it's a beautiful day here in seoul and nothing seems further away than a war. let's hope it stays that way. next, we find out that there's far more to north korea's military machine than rockets and bombs. in a conventional fight, there's no doubt that americans will own the air space. but what happens if the fight moves to cyberspace? >> on a scale of one to ten,

where would you put the threat level from north korea? >> definitely somewhere between eight and ten. >> are we ready for a new kind of war where the front line is actually online? stay with us. [ click ] [ keyboard clacking ] [ clacking continues ] good questions lead to good answers. our advisors can help you find both. talk to one today and see why we're bullish on the future. yours.

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welcome back to seoul, south korea. north korea, just 35 miles away from here, is one of the poorest countries in the world. it's also the most isolated. very few people have access to the internet and those who do are generally high-ranking government officials. and yet, it turns out there's a direct line connecting pyongyang, north korea's capital, with the most expensive leak in hollywood history. >> hello, north korea! >> one thing the north korean regime is not known for is a sense of humor. so when sony pictures was about to release a movie "the interview," which used the great leader as a pun in a dirty joke.

>> president kim jong-un -- >> a weapon was launched. it wasn't a missile or a bomb. instead, it was a sneak tobacco. >> they wiped everyone's computer and then they left this. >> eric chen traces down hackers for a living. he's the director of technology and response at symantec labs, one of the world's largest internet security companies. >> and then they had this scrolling message saying they're going to release all of their data to the world. imagine you come in and you're working at sony and tens of thousands of computers across your network are all infected and they're all displaying this. >> sony's servers had been ransacked. now unreleased movies were getting leaked online, internal e-mails, personal data, social security numbers, all posted on websites and social media. the attack cost sony about $42 million. that was back in 2014. since then, chen and other security experts have pieced the evidence together. they now believe the so-called

guardians of peace were none other than a hacking outfit better known as lazarus. >> we believe they're extremely well-funded, organized group of hackers, basically, basically h political reasons and also we see now for monetary reasons. >> reporter: lazarus, closely linked to north korea. its members combine attacks on known targets of the a shooregi hacking for profit, the digital equivalent of robberies. what digital detectives in the west didn't know was that lazarus was about town leash its first global attack. now to the massive cyber attack -- >> reporter: a piece of malware that sat dormant in millions of computers, activated friday, may 12th. fedex, spain's phone company, a trin compa train company and britain's

organization hit hard. >> wide-scale disruption. >> reporter: what benefit does north korea get out of it. >> it's unclear. the one thing that makes sense, simply they're unpredictable. >> reporter: another thing that makes the group uncontradictable. wannacry wormed its way into millions of computers but the code so basic a 22-year-old hacker from britain found an easy way to kill it only 48 hours after it was activated. >> this is wannacry on the right and a previous lazarus piece of software used in bangladesh. >> reporter: the attack on the central bank of bangladesh was a straight-up bank robbery, cyber style. no guns, no masks. just lines of code. the hackers exploited a small glitch in the global banking system and almost stole $1 billion -- except, they couldn't spell. >> the first indication that caused banks to go, wait a second. why is this transaction being made and held up the rest because of a single typo in the

organization name they were transferring the money to. one letter wrong. spelled it wrong. >> reporter: turns out an attack on a movie studio repeated attacks on south korea all came from one source -- eric chen connected the dots and cracked the case. >> it's very clear this is all the same group. >> reporter: their fingerprints are pretty clear, pretty obvious? >> pretty obvious and clear, they likely want people to know. >> reporter: because lazarus, experts around the world now believe, is no criminal outfit. it's an arm of the war machine operated by the north korean government. the u.s. government calls it "hiding cobra." >> i'm concerned about that north korea will decide to show that it can't be cornered. it may feel like it can't launch a missile, but north korea may calculate they can cause someone 20 back off by resorting to cyber attacks. >> reporter: robert silvers was in charge of cyber policy at the department of homeland security under president obama. he says we can't afford to

underestimate the cyber power the isolated nation of north korea can wield. >> people are always surprised because north korea is such a medieval society in many ways and yet have sophisticated high-tech capability to hack. the way they built it, also the way they at the same time are on the press pes of building an advanced nuclear capability. >> translator: the cyber war that started and no other country can attack north korea because there is no point. >> reporter: a former colonel in the north korea military who defected from kim jong-un came to hauo power. for years worked side-by-side with the hacking unit. notorious bureau 121. >> translator: only the very brightest students get to become hackers. they learn everything about the internet. then they work in the cyber research center, which is directly controlled by the

government. >> reporter: these hackers are all soldiers? they go to work in bureau 121 they're wearing uniforms? >> translator: yes. when they go from home to work, they wear their uniforms. they live in the military. they work for the military. ♪ >> reporter: it may seem at a time when the north korea are showing off nuclear capabilities and the u.s. is mobilizing enormous military assets the cyber threat is a minor concern, but keep in mind north korea is no match for the u.s. in terms of sheer military force. cyber attacks like terrorism are the kind of weapon that can level the playing field. >> it's a very asymmetric game here. imagine they did something to the u.s. brought down the power grid with their cyber attack, wiped a ton of machines. what does the u.s. do for retaliation from a cyber persecutive? north korea doesn't rely on this system. the financial system isn't built on computers all over the world.

>> reporter: one of the only countries not online? >> right. that will have zero effect on them. >> reporter: the challenge, there are not many krib targecy targets. we have much more to lose. >> our entire economy depends on the internet functioning properly. that's not the case for north korea. >> how would you rate their abilities? >> interestingly, look at them in relation to other attacks we've seen, low on the sophistication scale but their impact extremely high. >> reporter: scale of one to ten, threat level? >> somewhere between eight and ten. >> reporter: eight and ten? that's high. >> they're willing to do all kinds of really brazen things. >> reporter: and launching a cyber attack on our hyper connected society is much easier than launching a nuclear strike. so, please, update your security

software. our national defense may depend on it. you're watching "on assignment" with me, richard engel. back after a short break. stay with us. here in texas, communities answer to such evil unity in the comfort of friends and strangers alike. >> today everyone's family and we're not going to leave our brothers behind. >> democrats, republicans, but all one. >> yeah. >> his purpose is simple. deliver the mail, finish the route. >> we are seeing so many powerful images of hope that remind us that even in the worst catastrophe, the best can come out in people. paying less for my medicare? i'm open to that. lower premiums? extra benefits? it's open enrollment. time to open the laptop... ...and compare medicare health plans. why? because plans change, so can your health needs. so, be open-minded. look at everything-like prescription drug plans... and medicare advantage plans from private insurers. use the tools at medicare.gov. or call 1-800-medicare.

open to something better? start today. ♪ your body was made for better things than rheumatiod arthritis. before you and your rheumatologist move to another treatment, ask if xeljanz xr is right for you. xeljanz xr is a once-daily pill for adults with moderate to severe ra for whom methotrexate did not work well. it can reduce pain, swelling and further joint damage, even without methotrexate. xeljanz xr can lower your ability to fight infections,

including tuberculosis. serious, sometimes fatal infections, lymphoma and other cancers have happened. don't start xeljanz xr if you have an infection. tears in the stomach or intestines, low blood cell counts and higher liver tests and cholesterol levels have happened. your doctor should perform blood tests before you start and while taking xeljanz xr, and monitor certain liver tests. tell your doctor if you were in a region where fungal infections are common and if you have had tb, hepatitis b or c, or are prone to infections. xeljanz xr can reduce the symptoms of ra, even without methotrexate. ask your rheumatologist about xeljanz xr. we'll keep reporting for the foreseeable future. as were said at the beginning, there is no problem more in need of a solution, no crisis more urgent than the one that is unfolding here. north korea's now whether the world is ready to admit it or not a member of the so-called

nuclear club. that's not the only reason to ring the emergency bell. a war here could still kill an unthinkable unacceptable number of people. even in a conventional war scenario, the city behind me would suffer a prolonged deadly bombardment. it's not just that the south koreans are our allies. the issue, we've been involve ared in this conflict for 64 years. helped build this prosperous inundated and densely populated country and cannot allow it to end up in ruins again. president trump traveled here this week bringing the spotlight of world attention with him, trying to work with other countries to solve this crisis and that has to be a good thing, but this game of chicken playing with kim jong-un, the military escalation and trading of insults is a dangerous game. we should all hope the president is right. we should open hope that kim jong-un folds and gives up his nuclear program. if he doesn't, if he plays this game to its better end?

i think we've said enough how dangerous that could be. rachel will be back here monday night and next friday an exclusive investigation into the president's international businesses. you're not going to want to miss it. for now, good night from seoul. we've never before had an american president take office with so many -- um -- live business interests. not to mention business interests he didn't extract himself from before taking the oath of office. president trump kept his business interests for the most part. he did past ds day-to-day real street his sons and daughter and son-in-law joined the administration with high-level positions creating an historically unprecedented situation in which we really don't know if the president of the united states and his family are using his position to enrich themselves. that kind of concern is one of the main reasons presidential