on the broadcast here tonight, not ruling it out. tonight in our conversation with president obama, he leaves the door open to arming those rebels in libya. and we'll go inside libya for a progress report on the fight against gadhafi. maximum alert tonight in japan, where it now appears the emergency at the nuclear power plant will not be contained any time soon. is there a link between our children's behavior and the coloring in our food? the government is taking on the question again, while some parents have already acted on their own. and making a difference for people still struggling after katrina. tonight, the good people who show up and go to work every day without being asked.

"nightly news" begins now. captions paid for by nbc-universal television good evening, a few hours ago here in new york, president obama sat down to talk with us about the dangerous situation in libya and that entire region of the world. we asked him about the speech to the nation he delivered last night, the dangers of u.s. military involvement, while already fighting two other wars, and the precedent this may set in other nations. and the fact that this may not go quite as the u.s. and nato have planned. notably, as you're about to hear, the president left open the possibility of arming the rebels who are in the fight against gadhafi in libya. and here now a portion of our conversation with the president at this time of high stakes overseas. the moment your speech ended

last night, the associated press put out an item that read, president obama's speech was about defending the first war launched on his watch. how does it end? >> well, first of all, i think it's important to note that we've had two wars on my watch. one which we've wound down and we do not have combat operations in iraq any more. afghanistan, obviously, is still a tough fight. and that weighs heavily on me in making these decisions. but what was clear to me was we had a unique circumstance to save a lot of lives in this libyan situation. and that we had an international mandate to do it, and an international coalition that was prepared to share the burdens. what we've also done is put gadhafi back on his heels. and so our expectation is, that as we continue to apply steady pressure, not only militarily, but through other means, that gadhafi will ultimately step down. >> what if it doesn't work, what

if the rebels find themselves bogged down, this becomes protracted? >> well, keep in mind that what we've already done is transitioned, so that this is now a nato and international mission. our role is to provide support, intelligence, jamming capabilities, refuelling capabilities. and so we have been able to spread the burdens of maintaining a no-fly zone and protecting civilian populations, and we can do that for quite some time, precisely because we built a strong coalition to make it happen. gadhafi's been greatly weakened, he does not have control over most of libya at this point. >> how do you not offer the rebels direct assistance of some sort? >> well, we will be providing them direct assistance -- >> military? >> secretary clinton was in london for a conference today, at which multiple countries pledged to provide assistance. most of the assistance initially is going to be nonlethal assistance.

humanitarian aide. they may need communications equipment. they may need medical supplies. potentially transportation. >> with due respect, mr. president, watching the reportings of our two correspondents in libya, what it appears the rebels need is military equipment. some of their equipment dates back to world war ii. are you ruling out u.s. military hardware assistance? >> i'm not ruling it out, but i'm also not ruling it in. we're still making an assessment, partly about what gadhafi's forces are going to be doing. keep in mind we've been at this now for nine days. and the degree to which we've degraded gadhafi's forces in those nine days has been significant. operations to protect civilians continue to take out gadhafi's forces, his tanks, his artillery on the ground. and that will continue for some time. one of the questions that we want to answer is, do we start getting to a stage where

gadhafi's forces are sufficiently degraded, where it may not be necessary to arm opposition groups? but we're not taking anything off the table at this point. our primary military goal is to protect civilian populations and to set up the no-fly zone. our primary strategic goal is for gadhafi to step down so that the libyan people have an opportunity to live a decent life. >> a few weeks from now, if a member of your circle makes an impassioned case to do the same in syria, to finally decouple it from iran, what do you do? >> i think it's important not to take this particular situation and then try to project some sort of obama doctrine that we're going to apply in a cookie cutter fashion across the board. each country in this region is different. our principles remain the same. we want to make sure that governments are not attacking their own citizens. we believe in core fundamental

human rights like freedom of speech and freedom of assembly. we want governments that are responsive to their people. and so we'll use all our tools to try to accomplish that. but libya was a unique situation where a limited military intervention, that had a strong international mandate and strong international participation could make the difference -- life or death difference for a lot of people. and in that situation it made sense. that does not mean that somehow we are going to go around trying to use military force to impose or apply certain forms of government. >> so when people hear words like values and interests and your phrase, the flow of commerce, which some people couldn't help but substitute oil, they shouldn't think that there is any blanket policy. this may be an ad-hoc business if this so-called arab spring turns into arab summer, and we keep at this, watching countries change? >> well, what is absolutely

true, is that when you start applying blanket policies on the complexities of the current world situation, you're going to get yourself into trouble. and i take the application of military force very seriously. because even in a situation like libya, there's still risks involved. you saw that we had a plane malfunction. thank goodness we were able to retrieve those pilots. but it's conceivable that they could have been lost. and so in each of these situations, the application of force is something that, from my perspective, you preserve and are very careful to use. and there are going to be some people who get frustrated by that. why can't we fix this right away? why can't we impose our will? and it's my job as president to make those decisions based on all the consequences, understanding that we have some experience here in trying to impose our will in places like iraq. and i think the american people

understand the cost of that. >> i asked the president about all the other countries where uprisings have started, like bahrain and yemen and others, and again, he called libya a unique case requiring military action. you can see our entire interview online on our website, nightly.msnbc.com. now we want to go to libya and our chief foreign correspondent, richard engel. he remains in the rebel city of benghazi tonight. you just heard the president tell us gadhafi is back on his heels, the question is, does that match what you're seeing on the ground? >> reporter: good evening, brian. he may be on his back heels, but gadhafi is certainly still fighting. gadhafi's forces are crushing the rebellion in misrata, and today launched a powerful counteroffensive here in the east. at times today the rebel front line looked more like a desert rally than a military campaign.

rebels in cars, speeding away, retreating. with tanks, artillery and flanking maneuvers, gadhafi's troops easily drove the rebels back, far away from gadhafi's hometown of sirte. from a safe distance, the rebels fired back, but they're well out of range. >> we need the air force to help us. that's what we need. without them we can't do anything. >> reporter: witnesses say gadhafi is also planting land mines in the desert, making any ground advance even more difficult. but the worst fighting appears to be in the west, in misrata, deep inside gadhafi's territory. a rebel leader told us, saving misrata today is as urgent as saving benghazi was two weeks ago. >> it is the abuse in misrata. they have taken women out of their homes. they have assassinated people on sight. they have put snipers on top of the buildings.

they are stopping -- i mean mr. obama yesterday mentioned miss rat ta by name. >> reporter: in the rebel capital, benghazi today, president obama's speech was universally welcomed. at the rebel's radio station, free libya, anchors stressed that the united states won't topple gadhafi militarily, but will help libyans do it themselves. at a coffee shop downtown, men remain grateful for the american intervention. >> i'd like to show my gratitude to him. i appreciate what they've done for us, really. >> reporter: but on the front line, it's clear that without sustained western air support, the rebels can't take territory or hold it either. rebels here, brian, are starting to realize that simply driving to the front line and then turning around whenever they see gadhafi's troops isn't accomplishing anything. and that the rebels need more discipline, training and, as you asked the president, they want more weapons. >> all right, richard engel in benghazi, libya, tonight. richard, thanks. and as richard made clear, all

libyans are paying attention to what president obama is saying and doing about their situation. the president keeps talking about nato taking over this mission. that hasn't happened quite yet, and nbc news has learned because of a hitch, there's been a delay until at least the end of this week. meanwhile, secretary of state hillary clinton met in london today with u.s. allies and libyan opposition leaders to up the pressure on gadhafi. our chief foreign affairs correspondent andrea mitchell has been following all this with us tonight from our d.c. newsroom. andrea, good evening. >> reporter: good evening, brian. as richard reported, the rebels want weapons. as the president told you, he has not ruled that out. john mccain and others in congress are pressing again today to arm them. in london today, hillary clinton's focus was getting to know the opposition leaders. it's the second time she's met them in just the last two weeks, as the u.s. tries to figure out who would take over if gadhafi is forced out.

>> we don't know as much as we would like to know and as much as we expect we will know. we are picking up information. a lot of contact is going on. not only by our government, but many governments that are part of the coalition. so we're building an understanding. but at this time, obviously, it is, as i say, a work in progress. >> reporter: on capitol hill today, the u.s. nato commander acknowledged "flickers of intelligence about al qaeda influence among the rebels." but he quickly added the leaders of the rebels were responsible men and women. the u.s. has not recognized the opposition yet, but it was clear today in london, that the u.s. and allies are taking steps toward a new government in libya without gadhafi. even without winning militarily, the opposition is winning acceptance with the world's political leaders. brian? >> all right. andrea mitchell, rounding out our coverage in washington tonight. andrea, thanks. we have a lot of other news for you. and up next, as "nightly news"

continues on a tuesday night, an admission today from japan about the current nuclear crisis. and later, the color of what we eat and drinking and the suspicion that it's affecting the behavior of some of our children. it's an old question, and now it's returned.

back now and turning to the crisis in japan. the prime minister said today the death toll has reached 11,000, and that his nation remains on maximum alert. and the japanese government admitted today its safety measures were not enough to protect a nuclear plant against the earthquake and tsunami that ended up crippling that fukushima facility. nbc's lee cowan reports from tokyo tonight. >> reporter: the weary workers struggling to keep japan's nuclear disaster from getting any worse are faced with an uncomfortable reality. the cure could be almost as bad as the disease itself. water is the key to preventing a full-scale meltdown, either

sprayed into the reactors from fire hoses or injected by pumps. but the water that goes in clean is coming out radioactive. the result of a probable leak in or near a reactor core. for now the stagnant water is enough to fill two olympic sized swimming pools is simply the lesser of two evils. the other option is a meltdown. today, japan's prime minister went before parliament. acknowledged that given the news, there's little cause for optimism. >> workers continue to remove highly radioactive water. >> reporter: so far the toxic water hasn't spread, but emergency containers and sandbags have been put in place to prevent it from further seeping into the soil or making its way to the ocean. here at tokyo's famous fish market, where frankly, if it swims you can find it. fears of radiation in the water have already taken their toll. business has plummeted, this fish monger tells me. although no one is catching

anything in the 12 mile exclusion zone. and so far, there is no threat to japan's seafood industry, rumors have spread. i used to see a lot of tourists, he explains. now, i don't see any. for the tsunami's youngest survivors, today was the first day back at class since the earthquake. at this single elementary school, 80% of the children were lost. an incomprehensible lesson to learn so young. imagine teachers forced to explain how photo albums survived while many of their students' friends did not. lee cowan, nbc news, tokyo. in this country, while it's hard to believe they're going to say this outloud, it appears california is going to declare the drought is over. governor jerry brown is expected to announce tomorrow the 3-year-old drought declaration has been lifted.

the snow pack in the sierra nevada is 159% over what it was last year. reservoirs throughout the state are above normal. while the governor's expected to ask californians to still be judicious in their water use, the dry spell is officially over for now after a winter of heavy storms. we'll take a break. when we come back, is the coloring in our food, affecting our kids' behavior? tonight, some families are not waiting for the final answer.

artificial coloring is back in the news along with a mystery that's been around for a while. is there a connection between certain colors in foods and beverages and hyperactivity or attention deficit behavior? the fda is looking for a link, and then the question becomes, is there enough evidence to ban them, or at least require warning labels? here's nbc's tom costello. >> reporter: 7:00 a.m. in the vann family home, and breakfast is in the blender. bananas, strawberries, orange juice and a muffin on the side. three years ago, when 8-year-old riley was showing signs of adhd, his mom threw out every food containing artificial dyes and flavors. >> in two weeks i could tell a difference in my children, in their handwriting, in their focus, doing homework. >> reporter: here's riley's handwriting before the new diet and several weeks after. now the government is once again

looking at blue 1 and 2, yellow 5 and 6, red 40 and red 3. found in everything from drinks to candies, baked goods, chips, even pickles and mac & cheese. many doctors, researchers and consumer advocates have long argued there's a link between the dyes and hyperactivity. >> there's something genetic that is going on. but along come food dyes and they can trigger it in at least some kids. >> reporter: this controversy isn't new. since the 1970s, the feingold diet has been all about healthy eating and eliminating dyes from kids menus. now there are signs the fda is changing its opinion. the fda has always said there is no evidence of an adhd link, but now says the data suggests the condition may be exacerbated by exposure to a number of substance in food, including but not limited to artificial food colors. today the grocery manufacturer's of america insist there's no link to adhd, and we're always producing the safest possible product for our consumers.

now an fda panel will decide whether food dyes are safe enough to remain on america's store shelves. tom costello, nbc news, washington. tonight, the fbi's trying to figure out how it is a bullet hole's been discovered in a usairways 737 that last flew from philly to charlotte yesterday. it was discovered upon landing. officials tell nbc news it was a .40 caliber round that penetrated the skin of the aircraft. it was found inside. it appears from the angle of the trajectory, it entered the plane from above. they say there's no reason to believe it was anything other than a freak occurrence. when we come back here tonight, our "making a difference" report on the people who sometimes beat the first responders in their rush to help.

it's time now for our "making a difference report." and in our line of work we show up at a lot of disasters. and often the first people we see arriving on the scene to jump in, help out and rebuild are the mennonites. hurricane katrina was no different. we saw them, they arrived right away, and without fanfare and they are still there, on the job every day, volunteering to

rebuild and restore and to make a difference. their story tonight from nbc's kerry sanders in grand bayou, louisiana. >> reporter: on a slow trip into grand bayou, where five years on, recovery from hurricane katrina is still a way of life, cajuns who live here say to this day they know little about those strangers who dress old school and speak dutch. >> i think it's great. they're helping out a bunch of people. a bunch of my people here on the bayou. >> first, a dozen mennonites from wisconsin and western canada started to come to louisiana in the weeks after katrina. then thousands, and they're still coming. as is their way, they're still volunteering quietly a week or two at a time. >> here are two houses that we built over here. >> 97 houses and more to come. >> it's a culture of service.

mennonites, like amish, grew up with the idea that you help your neighbor. when your barn burns down, you rebuild it. and a neighbor may be someone across the country. >> reporter: dwight and his wife lived 4.5 years on his fishing boat. >> that's our kitchen, bedroom, living room all together here. >> reporter: about as much room as a prison cell. all this was built here? >> yes. >> reporter: he said, when outsiders promised him a new home and wanted nothing in return, he was skeptical. >> you thought to yourself? >> i thought, what is going on? people from nowhere, we never heard of, came here to help other people. >> reporter: not all the mennonites we met were willing to be on camera, because they said it would cause them to stand out. in an effort to remain humble, they asked we not use their names. >> we don't have to know somebody to do good for somebody. >> reporter: mennonites at home,

making homes for those in need in cajun country. kerry sanders, nbc news, grand bayou, louisiana. >> terrific story. and that's our broadcast for this tuesday night. thank you for being here with us. i'm brian williams, and we hope to see you right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com right now at 6:00, oakland's police department wants to change how critics see it by changing the way they see complaints. the important role technology is playing in all of this. >> also a. mountain lion putting a peninsula emergency system to the test today. >> and ready to shake it up, these kids get a big lesson in earthquake preparedness with a little help from the silicon valley.