nation. north korea's young leader carried out his threat today, cancelling the 60-year truce that ended the korean war. a step experts say could lead to a dangerous miscalculation. north korean soldiers being whipped into a near frenzy against the u.s. they shout "destroy american imperialist aggressor, the deadly enemy of north korean people, destroy, destroy, destroy." firing them up, their untested young leader kim jong un. inspecting fortifications across the waters from the demilitar o demilitarized zone with south korea. he told the troops to be ready to annihilate the enemy at any moment. so far a war of words as kim jong un tries to prove his strength and test south korea's newly elected female president, park geun-hye, who held her first cabinet meeting today. as troops held annual exercises, experts worry the threats could get out of control.

>> this young leader clearly has displayed some very unpredictable behavior. whether it's firing missiles in weeks following an agreement with the united states or whether it's meeting with dennis rodman. >> reporter: kim cancelled the hotline between north and south. all this prompting a stern warning from the white house. >> we are certainly concerned by north korea's bellicose rhetoric. >> reporter: the white house pressured china to stop kim before it's too late. >> we believe that no country, including china, should conduct business as usual with the north that threatens its neighbors. >> reporter: pyongyang is so desperate for cash it hasn't cancelled access from south korea to a shared factory zone just across the border. a major concern is that the threats will misfire, leading to a shooting war with america's south korean allies and instantly engaging the united states. brian? >> andrea mitchell watching with the rest of us from our d.c. newsroom. andrea, thanks. well, the start of the conclave is now just hours away

as the cardinals of the roman catholic church gather to select a new pope in a highly secret proceeding. nbc's anne thompson remains at the vatican for us tonight following it all. anne, good evening. >> reporter: good evening, brian. on the eve of the conclave there is no clear front runner. coalitions are forming but this is thought to be a wide open contest for the future of the catholic church. in their final meeting before the conclave, signs of collegiality disguise what some say is a growing divide among the cardinals. on one side the reformers including most americans who want to clean up the vatican bureaucracy and energize the church. versus the old guard represented by the italians. >> this is a contest between institutional maintenance and full bore evangelism. >> reporter: battles for control make rome feel like new hampshire during primary season. sunday masses took on the aura

of campaign rallies with italian parishioners in each church cheering on their man. italy's newspapers speculate angelo scola of milan has the most votes, but short of what's needed for election. canada's mark ouelette heads the congregation of bishops. boston's sean o'malley has repaired three diocese rocked by clergy sex abuse. he's charmed the locals with his monk's robe, sandals, and humility. >> let us praise the holy spirit to choose a new pope who will confirm us in our faith and make more visible the law of the good shepherd. >> reporter: today the drapes went up on the balcony where the next pope will first appear. the sistine chapel's chimney is ready to signal the news. from the secret proceedings under michelangelo's ceiling. these may be the most famous stoves in the world. this on the right is where the ballasts are burned.

on the left is where chemicals are put in to signify if there is a pope -- white smoke -- and if there is no pope -- black smoke. in the so-called room of tears next to the chapel wait the vestments for the new pope in small, medium and large. tonight, american seminarians pray for their next leader. tomorrow, the cardinals celebrate mass at st. peter's and in the late afternoon they will go into the sistine chapel where, in complete secrecy, cut off from the world, they are expected to cast the first ballot. brian? >> anne thompson with tonight's update from the vatican. thanks. we turn now to afghanistan. for the first time in two months there were american casualties in the war today. two u.s. service members killed in yet another insider attack. an afghan police officer opening fire during a briefing at a police station. happened in a province outside kabul hours after the new defense secretary chuck hagel completed his first trip to afghanistan. a solemn day in japan to mark the second anniversary of the earthquake and tsunami that

left almost 19,000 people dead. there were moments of silence and prayers throughout that nation. some 300,000 people are still displaced from the disaster which, of course, also destroyed the fukushima nuclear power plant. two years later as well, debris continues to arrive on our western shores. a 4.7 earthquake got the attention of a lot of people in southern california today. the epicenter was in riverside county in the san ysinto fault. it was felt in the valley, downtown l.a., about a hundred miles away and as far south as san diego. no damage or injuries. while unimpressive by southern california standards it was the strongest quake numerically in the l.a. area in three years. the story making headlines in the health world tonight is about women. a regular dose of aspirin and its power in preventing melanoma.

it has focused even more attention on the many uses and many wonders of aspirin. our report from our chief medical editor dr. nancy snyderman. >> remember, doctors recommend aspirin. >> reporter: for years this simple pill sold over the counter in stores across the country has been the go-to drug for aches and pains. increasingly aspirin has been called a wonder drug with evidence it can reduce the risk of heart attack, stroke, even some cancers. now in one of the largest studies of its kind new research suggests it may reduce a woman's chance of developing malignant melanoma, the most dangerous type of skin cancer. >> this is important. melanoma is increasing and on the rise in women. there are no great preventive strategies besides sunscreen and sun avoidance. >> reporter: using questionnaires this observational study followed 60,000 caucasian women ages 50 to 79.

they were put in three groups. those who took aspirin only. those who took nonaspirin nsaids like ibuprofen or naproxen, and those who took neither nsaids nor aspirin. during an average follow up period of 12 years 548 women developed melanoma. they found women in the aspirin-only group were the least likely to develop the disease. some 20% lower than the other groups. and the longer they took it, the fewer cases there were. researchers took into account factors like prior skin cancer, sun exposure, sunscreen use, skin type and tanning habits. >> we found women who took aspirin for greater than five years had the greatest amount of protection against melanoma. >> reporter: with more than a million cases of skin cancer diagnosed in the u.s. each year, any chance those numbers may diminish gs attention. it gets attention but also a reminder that the use of aspirin is not to be used lightly

because of the risk of bleeding. it is not a substitute for anything like covering your skin, sun tan lotion or just covering up. nonetheless, brian, tonight, very interesting. >> another wonder for the list of the wonder drug. >> it is. you couldn't get it on the market today. it would cost $1 a pill. >> nancy snyderman, thank you as always. surprising story in new york tonight. it is about health but also civil liberties and the reach of government. mayor michael bloomberg famously tried to ban large fountain drinks in the city as an effort to combat obesity. but a judge has said no. he stopped the order and now the mayor is saying this isn't over yet. our report on all of it tonight from nbc's rehema ellis. >> reporter: the ruling from the new york state supreme court judge came this afternoon, stopping new york city from

banning large sugary drinks. in his ruling, the judge called the ban on drinks larger than 16 ounces arbitrary and capricious. >> he said it's arbitrary because the same drink could be covered at a restaurant and you could walk next door to the 7-11 and get the same thing. he said it doesn't cover all high calorie sugary drinks. >> reporter: some in new york welcome the judge's decision. >> there shouldn't have been a ban in general or a prop position. >> reporter: the american beverage association issued a statement saying the court ruling provides a sigh of relief to new yorkers and thousands of small businesses in new york city that would have been harmed by this arbitrary and unpopular ban. it's not the first time the mayor tried to enact laws to affect public health. he won court approval to force restaurants to post calorie information and ban artificial trans-fats in restaurant food. the mayor plans to appeal today's ruling. >> we believe the judge's decision was clearly in error and that we will prevail on

appeal. if we are serious about fighting obesity, we have to be honest about what causes it and we have to have the courage to tackle it head on. >> reporter: in a city of more than 8 million where health officials say the obesity epidemic is responsible for more than 5,000 deaths a year, the mayor says his fight to make new yorkers healthier will continue. rehema ellis, nbc news, new york. still ahead along the way for us tonight, where are all the penguins? our journey to the bottom of the earth and what it can tell us about what's happening to the rest of the earth. later, making a difference. ann curry reports on a new way to see the world for people who can't make the trip themselves.

we have a status report tonight on climate change and how visible it is in one of the most stunning places on the globe. if you have the chance in life to journey to the bottom of the earth to antarctica, you will see it unfolding in dramatic

fashion. nbc's kerry sanders is just back from there and has our report tonight. >> reporter: it is the waning days of summer in antarctica and there is an annual race on. penguins are hatching. parents nursing their chicks before the first swim in the southern ocean. often their last because of what lurks below. >> the leopard seal is a number one penguin killer. >> reporter: it's part of the balance of life here. leopard seals eat up to 25 penguins a day. some people say there are only two different types of penguins -- the white ones walking towards you and the black ones walking away. but there are 18 different types of penguins. more than half have reason to worry. >> look at that. >> reporter: in the last 50 years average winter temperatures here have risen 10.7 degrees. the national snow and ice status center measured the lowest sea ice cover in antarctica just six

months ago. ice in this part of the world is the foundation of life. see the watermelon and green colors on the glaciers? that's algae under the icebergs and the frozen ocean. that algae feeds krill. and those shirimp-like krill ar the main source of food for penguins, seals, and whales. less ice resulted in 80% fewer krill. why is it all happening? manmade global climate change, say an overwhelming number of scientists like fabrice genevois. >> you have to be either a liar or crazy not to understand that we are doing actually something on climate change. we are responsible of the climate change today. that's for sure. >> reporter: the remote and harsh nature of antarctica makes penguin counts inexact. scientists use time lapse cameras to count populations. in some spots the colonies of penguins known as adelie have dropped by a stunning 90%.

>> we should not kid ourselves in thinking that will not have consequences. we don't necessarily need to fear change, but it will change the world as we know it. >> reporter: like a canary in the coal mine experts say the penguins are giving us a warning. kerry sanders, nbc news, antarctica. >> when we come back, the list just out for americans tonight on what are called the worst places to retire.

that was a backdraft. you know there was a movie of the same name. this was the real thing captured on amateur video at a fire in harrison, new jersey. it went to six alarms. five firefighters were injured. a backdraft is what happens when a sudden burst of incoming air gives an air-starved fire a sudden and dangerous burst of fuel. next month president obama will award the medal of honor

posthumously to an army chaplain for his actions in the korean war. family members will accept on behalf of captain emil capon who continued to minister to his comrades under withering fire and hand-to-hand combat. he was with the first cavalry and spent time as a p.o.w. we heard from a beloved tv star about facing down illness. in an interview that aired this morning on "today," savannah guthrie sat down with valerie harper who days ago announced to the world she has incurable brain cancer. >> at first i thought, oh, my god, three months to live. it's not the whole truth. yes, that may be. but it could be six. it could be five years. you know, you just don't know. but i'm also quite ready to say bye-bye. >> are you ever scared? >> sure. yeah. i'm scared for my family. i think of, you know, not going to christina's wedding.

but maybe i will. >> speaking hopefully there, as moms do about her daughter's wedding someday. valerie harper's discussion with savannah guthrie from this morning. snl had its highest rated outing in over a year for good reason. justin timberlake hosted his fifth time and was joined by a stunning club of other five-timers and then some. in smoking jackets no less, there was hanks and baldwin and short and chase and martin and bergen, simon and aykroyd for good measure. an incredible night spanning the history of the show from its earliest days. congratulations are in order for all of us. astronomers say we have dodged four more asteroids just in the space of last week. didn't even feel it. the largest was the size of a city block. and "u.s. news," as we mentioned is out with the ten worst places to retire. top three, bridgeport, honolulu and l.a. they have specific reasons for all of them.

the complete list of ten is on our website tonight. up next here this evening, making a difference with a whole new way of looking at the world.

>> announcer: making a difference, brought to you by pfizer. finally tonight our making a difference report is about a chance to see the world without ever leaving home. it's an innovative idea aimed at those who can't travel. thanks to technology and a growing number of photographers willing to let us eavesdrop on what they are seeing. our report tonight from nbc's ann curry. monica malone would love to travel the world. >> i had always wanted to go. >> reporter: to rome? >> yeah, to rome. >> reporter: but she can't move even a few steps without pain, much less make it up a flight of stairs. >> i'm going to just take a break. >> reporter: diagnosed at 15 with lupus which causes her immune system to attack her organs, she spent most of her life indoors. >> sometimes it feels like being stuck in a cage. you know, i can see out the window. i can log onto the internet. but those are my windows to reality. >> reporter: until she met a

photographer on a social network, google plus, and discovered there was a way she could finally see rome. >> look at this. >> oh! >> for a brief second i thought, wow. if i could only have a cup of cappuccino i'd feel like i was there. >> reporter: all because of john butterall who got an idea and thought, why not? >> one day i was out taking pictures and i thought, how cool would it be to attach a phone to your camera and hang out with five, ten people and they would see what i was seeing through the viewfinder of my camera. >> reporter: in one year some 200 other professional photographers signed on for what he calls virtual photo walks. >> can you see what i'm seeing at the moment? >> reporter: taking the disabled, hospitalized and elderly all over the world. encouraging them to help frame photos they want as keepsakes. >> right there. i like that a lot. >> reporter: these veterans in missouri got to virtual photo walk to pearl harbor.

among them, world war ii veteran bill shackleford. he'd like to meet the photographer. >> i appreciate it very much. i would like to thank the gentleman personally. >> reporter: monica hopes nobody will have to feel as lonely and isolated as she did. >> this has the potential to affect, especially so many children's lives. if they can just interact with people and know that the world has not left them behind. >> reporter: someone wrote your name in the sand. >> that's in hawaii. yep. >> reporter: you were there. >> yep. yeah. >> reporter: no longer alone, monica is now traveling the world. ann curry, nbc news, boulder, colorado. >> great idea to end on on this monday night as we start a new week. thank you for being here with us. i'm brian williams. we hope to see you right back here tomorrow evening. we hope to see you right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com

now. >> sex and the chris sanchez is live outside mountain view high where a parent meeting is scheduled. the concern has to do more with the content in the articles than the content itself. >> you hit that one right on the head. a lot of the parents were very quick to point out that this is not about sex. this is really about making sure

that the students are being good journalists presenting solid and accurate information that is appropriate to the young audience. we talked with one of the student journalists who says she is ready to listen at the meeting and learn from the experience. the high school newspaper, the oracle, looks great and discusses a variety of topics. highlighted in the issue sex and relationships. the photo editor says they want to talk about what teens are talking about. >> when we wrote the articles they were always meant to inform. >> reporter: earlier they talked about drugs and the fact that some parents let kids smoke marijuana at home. the incomplete information in that article and other articles related to sexual health mean students need more oversight. >> one talked about how you

needed to get yourself tested and you could use oral contraception and be fine. there is this idea being promoted that oral contraception equals protection against stds. >> reporter: the parents want the school to adopt a journalism code of ethics and for the students grades to be tied to what they produce for the newspaper. >> i think some of the things haven't seemed professional. we realize they are students and they are learning. there is nothing wrong with that. all of us have been there. it is just realizing that editing from an adult doesn't have to be called censorship. it can be helpful. it can be part of the writing process. >> reporter: she says she hears where parents are coming from and she gets it. >> we are not going to comple completely sacrifice ourselves and will be mindful of that in the