on our broadcast tonight, twin crises to report tonight. in libya, president obama announces the u.s. will now lead military action to stop gadhafi's brutal crackdown. and in japan, the nuclear crisis goes up a notch, increased to a higher alert level. what will it take to cool down those reactors and prevent a nuclear meltdown. our teams are on the ground across the world and "nightly news" begins now. captions paid for by nbc-universal television a special good evening to our viewer in the west tonight.

tonight we have to take you on something of a tour of the world to cover the overwhelming amount of news going on. and while we have been focused on the disaster in japan, where the nuclear alert level actually went up a notch today, while it's been going on for exactly a week tonight, instead we must begin tonight back in libya. today president obama announced that on top of the twor wars we're fighting, the u.s. will now take the lead on possible military action in libya. the u.n. approved it last night. it started out as a no-fly zone but has grown into something perhaps bigger. a nato ultimatum of gadhafi of libya that the president says is non-negotiable. gadhafi declared a ceasefire today but not all of his people were told about it. so on this busy friday night we have correspondents around the globe. we begin with nbc's andrea mitchell on what it is the u.s. military is now a part of. andrea, good evening. >> reporter: good evening, brian. armed with the u.n.'s approval of military strikes and a no-fly zone, the president gave moammar gadhafi an ultimatum.

an immediate ceasefire or face military action. and tonight there is no sign gadhafi is backing down. this is what the u.s. and its allies are trying to stop. gadhafi forces pounding rebels in the western city of misrata. the rebels claim this video was taken today even after gadhafi's government announced a ceasefire. in fact gadhafi seemed determine to carry out a bloody threat he issued on the radio last night, to retake the rebel stronghold, benghazi. he said he would show no mercy and no compassion. all this prompted a grave commander in chief to issue a blunt warning. >> these terms are not subject to negotiation. if gadhafi does not comply with the resolution, the international community will impose consequences. the resolution will be enforced through military action. >> reporter: president obama spoke shortly after briefing 18 congressional leaders, including many wary of yet another military engagement in a third

muslim country. but in benghazi, rebels cheered last night's u.n. decision to come to their rescue. >> i am very happy. i am very happy. gadhafi, gadhafi -- >> reporter: as the fighting continues the president is sending his secretary of state to paris to consult again with the allies. >> colonel gadhafi's refusal to hear the repeated calls up until now to halt violence against his own people has left us with no other choice but to pursue this course of action. >> reporter: u.s. officials say air strikes against gadhafi forces would be led by the british and french, with an unusual arab coalition. support expected from jordan, the united emirates, qatar and kuwait. >> i can tell the house britain will deploy tornados and typhoons as well as air refueling and surveillance aircraft. >> reporter: president obama ruled out u.s. ground troops but not air power. u.s. officials say the u.s. role would be to provide intelligence

and surveillance planes and awacs to track gadhafi's air defenses. they would also provide aerial refueling to allied planes enforcing the no-fly zone. the navy already has warships in the mediterranean with warships with cruise missiles and two nuclear submarines. the u.s. is expecting the saudis and others to help pay for what they see as a short engagement, but they added there will be cost for the u.s. taxpayer. tonight libya claimed it would advance no further on benghazi, but u.s. officials say gadhafi forces have continued to shell rebel areas. there is no evidence of a ceasefire. brian. >> andrea starting us off in our d.c. newsroom. here we go. how is moammar gadhafi reacting to this ultimatum tonight? jim maceda is our man in tripoli. jim, there you are and so this begins and it's proven an act of folly to try to predict gadhafi's next move, but what are the likelihoods here? >> reporter: you're absolutely right, brian. i don't pretend to be the expert. i don't think we can overstate,

however, gadhafi's instinct for survival. he's managed to rule some 42 years through u.s. bombings and several coup attempts, so this crisis must be a little bit familiar to him. analysts who know gadhafi well say that he'll have to pull back his forces from some of the key towns in the east like benghazi. he's not stupid, they say, and he'll know now that his rule, his life, in fact, are at stake. he may try to negotiate a truce, try to cling to power in what some are calling a north african bosnia, rebels in the east, he and his family controlling the rest with some african or u.n. peacekeepers in between. but, brian, that's if the gadhafi, the pragmatist shows up. if it's the other gadhafi, who knows what will happen. >> jim maceda is on his post in tripoli. jim, thanks. now we shift to the middle east where as we mention governments are cracking down on protesters really without mercy.

most notably tonight in both yemen and bahrain. our chief foreign correspondent, richard engel, has made his way back to cairo tonight. he has more on the renewed violence against these uprisings throughout the region. richard, of course two things happen. the attention focused elsewhere shifted away and some of it died down, but here we go again. >> reporter: the arab revolts are once again gaining momentum and libya is not the only regime that is fighting for its survival. today both bahrain and yemen, both american allies, are taking a very hard line. and a warning, some of these images are graphic. the victims in yemen were rushed to makeshift infirmaries and chaotic hospitals. many were bloody, some motionless. witnesses say dozens of people were killed when tens of thousands of protesters were shot at by snipers. the protesters want to remove

yemen's president of 32 years, a u.s. ally in the fight against al qaeda. tonight saleh announced a state of emergency. he blamed the protesters for the crackdown and denied his police fired a single shot. he claimed armed yemeni citizens attacked the demonstrators because they were being disruptive. arab leaders are seeing that despite international pressure and media attention, old-fashioned force still works to stop rebellions. in bahrain, a bloody crackdown has been under way for days, with scenes like this. watch the man in red. first he's shot with what appears to be a rubber bullet. he falls, but stands up, clutching his chest. only to be shot again point blank in the head. in the capital today, the government bulldozed pearl square, bahrain's version of egypt's famous tahrir square. as if by knocking down the

rallying point for protests, the demonstrators would just go home. in neighboring saudi arabia today, a different approach. money for peace. there were celebrations as king abdullah raised the minimum wage, created 60,000 new jobs and pumped $4 billion into health care. to stop revolts once again gaining momentum, arab regimes are trying to buy off the opposition or crush it. the crackdowns in yemen and bahrain are particularly embarrassing, brian, to the united states since the united states has a great deal of influence in both of those countries, yet the violence continues. brian. >> so much in motion in that region once again. richard engel back on his post in cairo. richard, thank you. and now, again, we shift back to japan and the nuclear disaster we've been covering for days. two days ago, japanese officials shot down the american assessment that the situation at that plant was bleaker than they

were letting on officially. tonight, though, those same japanese officials have now raised the seriousness of the accident from a level 4 to a level 5 on a scale of 7, as they measure nuclear danger around the world. that puts this on par with three mile island here in the u.s. and there are new efforts again tonight to cool down those troubled reactors. our own robert bazell in tokyo again tonight. bob, good evening. >> reporter: brian, with a new day beginning here in japan, simultaneous efforts will resume to try to contain nuclear fuel at those crippled reactors, but the situation remains dangerous and out of control. as part of the desperate struggle to cool down the dangerous nuclear fuel, firefighters from the tokyo fire department hosed down reactor number 3. smoke rising from the plant shows the effort is at least partially successful. in the next effort, workers are hooking up electricity to try to

get the pumps running, but what if the pumps are damaged beyond repair. >> there's so many other factors, i'm not even going to start to guess how complicated that gets. >> reporter: beyond the reactor core pumps are needed to refill tanks like these containing the spent fuel rods. there's 1760 tons of fuel in the tanks, four times more than in the reactor. this photograph shows the damage near the fuel tanks at reactor 4. officials fear many tanks may have lost all or part of their water in the earthquake, leaving the fuel susceptible to damage and even explosion. shooting or pumping water is one solution. but there is great concern that some of the pools are too damaged to hold water. u.s. engineers have developed a plan to fill the tanks with sand and other materials. the japanese say this is not feasible, but outside experts disagree. >> the idea with putting sand in the spent fuel pool is that it provides protection so that they can come back in and put water or something else on. it's going to shield that, stop the radiation from leaking out, slow down all of what's going on and give them time to make the next step happen.

>> reporter: measurements taken by u.s. military planes show dangerous levels of radiation remain confined to the area near the plant. according to international agencies, the rates beyond the plant do not yet exceed dangerous levels. officials hope to have electricity hooked up to units 1 and 2 this weekend. if that is accomplished, it will be the first success in this highly dangerous battle. brian. >> bob bazell in tokyo. bob, thanks. in this country the federal government says no radiation levels of concern have been detected, but for the people of japan, the fear of a nuclear catastrophe is just a part of the story. the extent of the humanitarian crisis is truly staggering. nbc's ann curry reports from akita again tonight on that nation still struggling to cope with this disaster. ann, good evening. >> reporter: brian, good evening to you. that's right. here are the numbers to date. about 7,000 confirmed dead.

nearly 11,000 still missing. and today this disaster-exhausted nation paused for a moment, trying to come to grips with the week that changed it forever. sirens sounded across japan today, and people stopped to mark one week since the earthquake and tsunami shattered thousands of lives. rescuers paused in their work. evacuation centers grew quiet. the prime minister addressed his people. saying we cannot let ourselves be overcome. seven days into this crisis, the destruction in many towns remains so complete, it's now hard to imagine the thriving communities they once were. other cities like tono up north are ghost towns. little damage, but the people are indoors, fearing radiation. another town is struggling to get back on its feet. my colleague, ian williams, is there. >> reporter: all along this coast there are reminders of the

raw power of the tsunami. this fishing boat, one of several ripped from its moorings and simply dumped by the side of the road. this city survived the tsunami better than most, but here more evidence of the toll suffered by japan's elderly. they're exhausted and shaken, said the manager of this evacuation center. japan is a rapidly aging society. nowhere more so than in these devastated coastal communities. and the relief effort will increasingly have to focus on them. >> reporter: the snow and cold are still hindering efforts to get help to the furthest pockets of need. u.s. marines specially trained for bad weather flew supplies into yamagata today. international rescuers have little hope of finding any more survivors, but they are sustained by the measure of comfort they can provide to some anxious loved ones. >> yesterday we found a young

girl's body, an 8-year-old girl. we were able to send that back to her family. >> reporter: amid debris, there are what seemed like small miracles. one man found his cousin today after a full week of searching house to house. a woman reunited with her dog after all hope appeared to be lost. small but happy moments in a long week of grief and loss, unlike any this nation has ever seen. and international aid is now beginning to reach those areas that are hit hardest by the quake and tsunami, brian, and none too soon. >> ann, you've done such extraordinary work there. safe travels home. perhaps when you get back we'll have a moment to talk about all the images you took in during your coverage. ann curry in akita, japan, tonight. ann, thanks. we'll continue the broadcast in just a moment. when we continue, with people asking what all this means for japan, wait till you see what it did to chernobyl 25 years ago and what it's like there today. we'll take you back there tonight.

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the danger is still here. >> how much is it? >> 7,000. >> 7,000? should we even be standing here? >> reporter: more than 300 times the radiation there than would be normal. >> you have to say the next 300 to 1,000 years, it will not be possible to live normally or to have any economic development. >> reporter: but chernobyl was much different than japan's fukushima. it didn't have nearly the protection around the core and had flaws, like components that burned, spreading radiation across europe. marina was 19 then, a mile away. today she has thyroid problems. >> translator: you feel like an alien in this world because you can't go back home. something that was your own, close to your heart, and now it's gone. >> reporter: ukraine is now constructing a billion dollar

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in wisconsin today, a judge blocked wisconsin's controversial anti-union law which was the subject of weeks of protests, like we saw here. the judge granted a temporary restraining order, slapping a hold on the law while she considers a challenge from a county district attorney who is arguing that republicans violated state open meetings laws when they voted on it that night. even if the law is thrown out on those grounds, though, the republican-controlled legislature could turn around and pass it again. this is the kind of thing fitting with our over-the-top, uncontrollable pace of news of late, something they are calling the supermoon. tomorrow night the full moon will be the closest it's been to earth in nearly 19 years. it will look massive and very bright, especially when it's near the horizon. an optical illusion will make it look 16% bigger and 30% brighter than normal. the main effect will be very high tides in places where they're prone to it, some beach

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a moment of silence in the little tokyo neighborhood of l.a. last night, as there was in tokyo, marking the exact one-week anniversary of the quake that caused the tsunami that caused the nuclear emergency that will haunt japan for our lifetime. the people gathered to pause, to chant, some shared stories about what had happened back home and how it had affected their lives and families. and what a week it's been. when you think about it, what a year it's been so far. but this story we've been covering in japan has also offered its share of lessons. some have even found a way to find inspiration. among our correspondents on the story, we hear tonight from nbc's lee cowan. >> reporter: in just a single week in japan, the phrase "worst case scenario" has been redefined. words like "unimaginable,"

"unthinkable," even "unacceptable" are thrown about. even they don't convey the escalating horror. yet rising out of it all is evidence the human spirit can overcome even this. there's proof in the sacrifice of these chopper pilots, braving radiation as they fly low over leaking reactors. there's proof in the relief workers, who have rushed from more than 100 countries to toil in the snow and ruin. and most of all, there's proof in the workers inside that plant, the unseen heroes known as the fukushima 50, struggling to avert a meltdown. bravery comes in odd places these days. especially where things seem to have returned to normal. with no fuel, patrons at this restaurant are facing the real possibility of being trapped, if radiation comes. there's no complaining, though. instead, just a quiet determination.

>> if they told you you had to leave right now, what would you do? >> we have to die. >> reporter: we have to die. a kind of stoicism evident even in our viewer e-mails. our families are asking us, begging us to leave, one woman wrote, but part of me doesn't want to turn my back on the country that i love. a week ago japan was brought to its knees, and yet so many are still standing tall. maybe this trio of disasters did redefine "worst case scenario," but it also offered glimpses of the best the human spirit has to offer. lee cowan, nbc news, london. and a reminder that on our website we've posted some answers to frequently asked questions about this disaster in japan, and we continue to offer a list of resources for those americans who are looking for a way to give, to help. it's all on our website at nightly.msnbc.com. and that is our broadcast for this friday night and for this week. thank you for being here with

us. i'm brian williams. lester holt will be here with you this weekend having returned from japan. we, of course, hope we'll see you right back here on monday night. in the meantime, have a good weekend. good night. -- captions by vitac -- www.vitac.com right now at 6:00, digging deep to help the victims of the disaster in japan. the fund-raising effort helping in the bay area. we will show you how to help. plus, you don't see this every day, not even once a year. the wicked weather hitting the bay area. and thank you for joining us. >> we are used to heavy rains