on the broadcast tonight, paying tribute to america's fallen heroes. on this memorial day, somber ceremony and celebration. holiday politics. the palin bus tour rolls on. what is her end game? moving forward. after the storm in joplin, some of those who served on the front lines of war spent this day on the front lines at home. taking cover. a kindergarten teacher hailed as a hero. her students ducking and singing while gunfired raged just outside. and best friend. there's a reason they brought one of these fearless warriors to get osama bin laden. "nightly news" begins now.

captions paid for by nbc-universal television good evening. i'm kate snow in tonight for brian. on this memorial day when america honors the fallen, it's worth remembering u.s. military men and women are currently in harm's way in three fronts. in afghanistan, america's longest war. in iraq, where the combat mission is over but nearly 50,000 american troops remain as advisers, and now in libya as part of a nato support mission. we'll hear from some of those serving far from home on the broadcast tonight. first here in this country today, president obama paid tribute to american war heroes as he laid a wreath at the tomb of unknowns at the lincoln national cemetery, and he got a little personal, too. >> to those of you who mourn the loss of a loved one today, my heart goes out to you.

i love my daughters more than anything in the world, and i cannot imagine losing them. i can't imagine losing a sister, a brother, or a parent at war. the grief so many of you carry in your hearts is a grief i cannot fully know. this day is about you. and the fallen heroes that you loved. >> across the nation, people took time out for traditional holiday parades and picnics, of course. this one in chicago. further south in joplin, missouri, it was a day of hard work with significant numbers of veterans who served on the front lines pitching in to help at home now. ron allen is in joplin again tonight where it has been an especially somber memorial day. ron, good evening. >> reporter: good evening to you, kate. a holiday full of hard work here. searching for more victims while the survivors clear away the debris and keep trying to rebuild their lives. there's a significant number of

veterans who do live in this community. some hit hard by the storm, and some still willing and ready to serve. >> we've got a request -- >> reporter: joe sorento saw the horrors of three wars in 27 years of services, but this retired master sergeant is in awe of what he's seen in joplin. >> i have been in bombed areas. this is indescribable, what is happening in the neighborhoods. this one brought tears to my eyes. >> reporter: he directs a squad offering 4,000 free meals a day to the homeless and those helping. >> if i can touch one or two hearts out there, my job is done. >> reporter: dave baker, a navy vet, and his wife marsha reopened their battered flower shop with a strong message, triping to help joplin's grieving families with dozens of celebrations of lives lost in the weeks to come.

>> we're part of the community, people need us. this is one way we can serve. >> during his president, president obama promised the federal government would help joplin recover any step of the way. >> this is a national tragedy. that means there will be a national response. >> reporter: and he also praised the community for coming together. they paused here at 5:41 p.m. on sunday, exactly one week after the storm. a week that witnessed countless acts of neighbor helping neighbor and strangers becoming friends. >> couldn't tell you where everyone is from. >> reporter: dave brown, an army veteran, flies his flags on the hill where he's rebuilding his house and a local church. an old soldier determined to still take the high ground. >> once our neighbors see that and realize the old church on the hill is still standing, we're rebuilding, too. >> reporter: about 8,000 buildings were decimated here. so many homes destroyed that fema now says it may have to bring in some of the temporary trailers.

and late today, officials announced the search for survivors will soon officially end unless there's a miracle. >> we can only hope. ron allen, thanks. there's a new threat of severe weather in the plain states. also, a different kind of weather danger we're keeping our eye on for tomorrow. that's the heat. weather channel meteorologist chris warren joins us now for more on both of those fronts. >> kate, right now, we're seeing storms fire up in the plains. tomorrow, this is where we're going to see the severe weather threat. anywhere we see yellow and red, we're going to see strong thunderstorms. the red, though, this is we we have the best chance for damaging wind, large hail, and possibly isolated tornado. severe weather most likely in the red. talking about another area of red, this is where we're seeing a lot of heat. in fact, in chicago today, six people had to go to the hospital because of the heat. temperatures feeling more like peak summer. for some, this is the warmest it's been all year.

we're getting right into very hot weather. this is dangerous heat. add in the humidity, and we'll have temperatures that feel like in the triple digits for some. in facfact, some may get to triple digits in the south. and kate, when we see a cooldown for the mid-atlantic and the upper midwest, we'll be going from very hot to just plain old hot. not much relief in sight. on this day of rest and remembrance, there's another group hard at work. sarah palin's bus tour was continuing, raising her presidential intentions and several other candidates for presidential took advantage of the holiday to meet and greet voters. the question is, how many people are serious contenders? >> reporter: sarah paling taking stock of her options. she stormed the nation's capitol, stopping at iconic sites, including the national archives and mt. vernon. it's the second day of her bus

tour, but still, she's not answering the big question. >> are you going to run? >> yeah, we're still kind of contemplating that. >> reporter: but there are signs that palin won't jump in. >> she's not raising any money. she doesn't have a ground game in iowa or new hampshire or south carolina. she isn't in contact with any of these really important key figures in the party. >> reporter: the latest gallup poll shows palin is only trailing mitt romney by two points. the front runner is expected to announce his candidacy on thursday. >> what are you going to do to beat obama? >> i'm going to talk about the the one thing he doesn't want to talk about. >> what's that? >> the jobs and the economy. >> reporter: the gallup poll shows other republican contenders are far behind. ron paul at 10% down to michele bachmann at 5%. the minnesota congresswoman turned up today in new hampshire at a memorial day event. she said she would announce her decision next month. >> if i decide to throw my hat in the ring, i think i'll do very favorably against barack

obama. >> reporter: meanwhile, former minnesota governor tim pawlenty barn storming in another state, making the rounds in iowa. >> we're in a competition for the future direction of the country. >> reporter: even some party insiders say whoever enters the race will face a formidable opponent, president obama. >> he's a great candidate, prolific fund-raiser. just because republican voters don't like the president doesn't mean we can take that for granted. >> reporter: nearly 4 in 10 republican voters surveyed said they were not satisfied with the current choices. still, it's very early in this race for the white house. kristen welker, nbc news, washington. overseas now to yemen, a place where the current president has held power for more than 30 years, using deadly force to combat growing demands that he step down. today, some of the worst violence since the crisis began months ago. and all of this is of great concern to the u.s. which has a lot at stake if yemen becomes more unstable.

our chief foreign correspondent richard engle in is tripoli tonight with the latest on this volatile situation in yemen. good evening. >> reporter: good evening, kate. the violence in yemen is now starting to look like a civil war with serious consequences for both the region and the united states. the most serious incident today was in the series of taez where witnesses say at least 20 demonstrators were killed during a government crackdown. the crackdown started with water cannons and tear gas. then sharp shooters moved in. backed by tanks and bulldozers. they destroyed an entire protest camp in the city of taez. witnesses say some of the tents were crushed with demonstrators still inside. in yemen's capital, furious crowds blamed president ali

abdullah saleh, the u.s. ally in power for three decades. he's repeatedly refused to accept an internationally brokered deal to see him step down in exchange for immunity. stability in yemen is critical for the middle east and the united states. yemen borders saudi arabia, the world's leading oil producer and yom yemen is home to a powerful al qaeda cell that sent a nigerian with a bomb in his underwear to blow up an airport in detroit on christmas day, 2009. they mailed a sophisticated printer bomb last year. but some opponents say the yemeni president is now using al qaeda to stay in power. islamic militants linked to al qaeda took over a town there this weekend, but only after government forces withdrew. then today, saleh's troops bombed the town. yemen's opposition accuses saleh

of letting al qaeda in to prove he's fighting islamic militants, not pro-democracy demonstrators. >> the u.s. embassy called the crackdown both unprovoked and unjustified, kate. >> richard engle, thank you so much. back here at home, it's now official. president obama chose this memorial day holiday to announce his new chairman of the joint chiefs of staff. he's army general martin dempsey, a west point veteran and iraq war veteran who describes himself as an irish kid from new jersey. the next step, confirmation by the senate. still ahead, americans at war far from home. a young soldier and his platoon in one of the most remote places you can imagine. and later, they're brave, smart, and they never complain about the food. meet america's dogs of war, as "nightly news" continues on this memorial day.

we're back now with our special series "far from home." jim maceda has been profiling the men and women of the u.s. military who are doing the hard work of america's war in afghanistan. and we thought memorial day was a good time to tell the story of another one of these brave warriors. today, jim has the story of a young soldier from california who is very far from home in one of the most remote parts of the war zone. >> reporter: bageese, it means home of the winds. a remote province with no electricity or paved roads. for staff sergeant nick lewis and his platoon of calvary men, this is as far forward as it gets. >> like last time, we took contact with these guys, all right. throw some rounds down, all right? throw some rounds.

let them know we're okay. >> reporter: all of them are trigger pullers. and often, the police. >> which house is he living in is he living over here or over there? >> reporter: even the government. >> based on the intel, we could start helping out the village, help the workers, out, give them jobs. what's up, all right? >> lewis, 32, from san francisco, has made some afghan friends here but the taliban are never far away, waiting, watching. >> you're surrounding by mud. the mud is surrounded by a mud wall, and the mud wall is surrounded by the taliban. >> pretty much. that right there sums it all up. >> lewis' day evolves around his wood stove, staying warm and dry. >> they're close, dude. >> reporter: and keeping his men alive. the taliban launched this surprise attack from three directions, pinning down the troops for several hours. >> that was intense. and we're all safe.

>> reporter: and when this scout isn't fighting -- >> what's up, buddy? >> reporter: he's playing with the new mascot, or skyping home every other night to wife karina and his two daughters in colorado springs. >> i can't wait to see what you have done. i can't believe you laid all hardwood floors down. >> i keep myself busy. >> reporter: lewis said they are his rock. by age 18, he lost his mother, father, and grandparents and lost his way. smoked dope. a bay area stoner, he says, until boot camp turned him around forever. ♪ don't stop believing >> reporter: now, far from home, it's his military family that fills the void. >> good morning. i try to be like that father figure to them and look after them, you know, because they are my boys. >> reporter: lewis deeply believes in the power of service. >> i think it's a great honor to

serve your country, period. >> reporter: fighting to hold on to every inch of a barren piece of northwest afghanistan with few re-enforcements. >> they're shooting pretty far. >> reporter: but plenty of heart. jim maceda, nbc news, afghanistan. up next, a grainy video that's getting a lot of attention. you'll see why a kindergarten teacher is being hailed a hero as "nightly news" continues on this memorial day, 2011.

a cell phone video popped up on youtube this weekend that reminds us how devastating the drug war in mexico has become and how small the victims can be. a classroom full of kindergarten kids is singing a cute little song from barney the dinosaur all while a gun battle rages right outside their window. the story tonight from george lewis. >> reporter: the teacher's name is marta rivera, and this morning, mexican officials praised her courage under fire. on friday, organized crime gangs fought a gun battle that killed five men outside the school where she teaches. inside, she calmly ordered the children to lie flat. nothing is happening, sweethearts, just put your little faces on the floor. the teacher said she shot the

video because she's on the school safety committee and felt the need to record this. as they cower from the rainfall of bullets outside, she has the children sing a barney the dinosaur song about how it's raining chocolate. ♪ if the rain drops were made of chocolate, i would love to be there. >> the actions of the teacher in the situation were absolutely extraordinary. the primary objective is to keep the children safe and to keep them calm. >> reporter: this map from el norte pinpoints the instance of violence this year. an american teacher living in monterrey who wants to remain anonymous spoke to nbc news. >> it's happening everywhere. to actually see that video, it's just -- there's no way to escape the reality of what is happening here. >> reporter: children in mexico conduct shootout drills like the old duck and cover drills

american school children went through in the old cold war. this picture drawn by a child titled the mexico i live in, is hauntingly similar to children's drawings from kosovo, iraq, and other war zones. and this teacher from monterrey and the children in her kindergarten class know that terror all too well. george lewis, nbc news, los angeles. up next, these are definitely not the family pets. they're some of america's best warriors. we'll see what they bring to the fight. so

we close on this memorial day with a story about some four-legged friends who aren't exactly the cute and cuddly type. we all remember it was an elite unit of navy s.e.a.l.s who led the raid on osama bin laden's compound in pakistan, but they u.s. military also announced one of their canines played a big role that night. they call them war dogs, and tonight, we have been given access to a facility where those dog become true fighters. miguel almaguer reports from nevada. >> reporter: a training mission in the nevada desert. a simulated high-stakes overnight raid. the 99th ground combat squadron,

heavily armed, but one of their best soldiers doesn't carry a gun. these four-legged warriors, pursue, track, and attack. >> what they bring to the fight for us cannot be overstated. their senses are what are literally saving people's lives. >> reporter: today, 2,700 war dogs are on active duty. leaping into battle outfitted for war. radio callers relay orders, kevlar vests protect from gun fire. goggles they call doggles shield their eyes, but it's their nose the military depends on. able to smell up to ten times better than humans, these german and belgian shepherds are the best bomb detectors the military has. nbc news was given access during the intense training. only the best of the best would be deployed. during their nearly month-long

training at this desert facility, the canines and their handlers will go through virtually every possible experience before they hit the battlefield. the teams stay together for years, a bond that lasts a lifetime. the war dogs are fiercely loyal to their handlers, as we found out. >> as you can tell, if you come closer, he might try to go after you and attack. >> reporter: tech sergeant julian carlos spends more time with his dog than his family back home. 300 canines have died in the line of duty since the vietnam war. but it's been said every military dog saves 150 lives. >> they become my heroes. that's what i would classify them as. >> reporter: war dogs. more than man's best friend, a special breed of soldier. miguel alvarez. nbc news, las vegas. >> that's our broadcast for this monday night. thank you for being with us. i'm kate snow. brian williams will be back tomorrow. in the meantime, take a look at our facebook page.

many of our viewers told us how they spent this memorial day. we'd love to hear from you as well. have a great rest of the holiday, and we leave you with some images from across the country of this memorial day. good night. good evening, everyone. i'm garvin thomas. >> i'm jessica mcgeary. a stinky and costly situation running afoul on the ground. miles of sewer lines under homes of the city of san leandro now says it doesn't have to maintain anymore. alease kirchner joins