lester holt will be here with "nightly news." tonight, what did the president know and when did he know it? critical questions after the outster of the national security advisor. >> was nationa security at risk? finally justice for one of the first missing children on a milk carton. decades later, his killer found guilty. harrison ford scare. eye dangerous incident in the sky and faa investigation. shocking airport assassination. kim jong-un's brother poisoned. the healing power of love. one couple's amazing story this valentine's day.

"nightly news" begins right now. good evening to our viewers in the west. the story behind the late night resignation of michael flynn continues to unfold tonight. nbc news learning exclusive new details about who knew what and when about the true nature of flynn's conversation with the russians before the inauguration. the white house said today president trump asked for flynn's resignation calling it a matter of trust over flynn's misleading accounts of his dealings. but it didn't fully explain why now, weeks after the president was warned that flynn, who was privy to the nation's top secrets, might be vulnerable to blackmail by the russians. our team is working several angles to this story. kristen welker leads us off with late details. >> reporter: tonight

mounting questions at the white house after national security advisor mike flynn was forced to resign late last night after misleading the president, the vice president and others about discussing sanctions with russia's ambassador before the inauguration. >> this was an act of trust. whether or not he actually misled the vice president was the issue. that was ultimately what led to the president asking for and accepting be resignation of general flynn. >> reporter: the key questions tonight, what did the president know, when did he know it and why did the president keep flynn on board for nearly three weeks after the president found out he had been mislead? nbc news learned vice president pence was not told for 15 days after the president and white house knew. meaning, no one told pence that he had been sent out to say something false about flynn, the only reason pence was informed, apparently an impending media report that would cast doubt on pence's own honesty. >> why not immediately act? why wait another two

and a half weeks? >> i don't understand how that's a due process. it would be unbelievably wrong and short-sighted to dismiss someone immediately. >> reporter: this came to a head late last night amid revelations on january 26th, the acting attorney general informed the white house counsel about the call with russia, even suggesting flynn could be vulnerable to bla blackmail. the president's counsel informed him and other top officials. >> we had to review whether that was a legal issue which the white house concluded was not. >> reporter: the counsel informed him and other top officials. who said they had broader concerns. >> this was a policy and ethical question, not simply a legal question. it's not good policy having the national security adviser out and about, conducting big national policy. >> reporter: the white house insisting the president didn't give the order to talk about sanctions but acknowledging mr. trump doesn't see a problem with it. >> the president had no problem with the fact he acted in

accord with what he's been doing. >> reporter: the white house has been under fire over flynn since president trump took office. december 29th, flynn spoke to the ambassador the same day obama imposed sanctions. one day later, russia's president putin stunned the obama white house announcing he wouldn't retaliate. january 12th, a bomb shell in the "washington post." flynn and the russian ambassador talked about sanctions and the call was recorded. january 15th vice president leath mike pence protecting flynn, playing defense, by insisting sanctions never came up on the call. >> it was strictly coincidental. >> reporter: six days after the president was sworn in, he was told about what really happened on the call and while negative headlines piled up, even as late as yesterday afternoon, top advisers were adama adamant. >> does he have the full confidence of the president? yes, he does. >> reporter: just before 11:00 p.m., flynn was out.

tonight an administration official tells nbc news the vice president is disappointed about being misinformed by flynn but respects his service. sources add there will likely be a replacement by the end of the week. the search started as early as last week. an indication flynn's ouster has been in the works. >> kristen welker at the white house, thank you. as flynn's forced resignation rocks the trump administration, the scope of the fallout is still being assessed. it puts into question whether flynn could have put national security at risk. nbc news' andrea mitchell has that part for us. >> reporter: tonight mike flynn's sudden ouster raising critical new questions about the damage to national security, and the russian connection. for weeks, flynn was giving the president talking points for phone calls with heads of state, including fld fld, threatening iran. >> as of today we are officially putting iran on notice. >> reporter: even last weekend at the dinner table conference as seen on social media on how to publicly respond to north korea's missile launch

despite the justice department being warned last month that flynn might be vulnerable to blackmail by russia. >> michael flynn who was from the moment the president was inaugurated a counter intelligence risk. >> reporter: the risk, vladmir putin knew what flynn had told the russian ambassador last december, while the vice president and others did not. nbc news has learned from two former intelligence officials flynn signaled to the russian ambassador, president trump might ease off on obama's russian sanctions. critics say that knowledge could give putin a special hold over president trump through his national security advisor raising big questions about flynn's advice to the president on russia and mr. trump's startling defense of putin. >> putin's a killer. >> a lot of killers. we got a lot of killers. you think our country is so innocent? >> reporter: all while the u.s. is investigating russia's hacking. >> flynn was secretly communicating with russian officials at the same time that russia was attacking

our democracy. >> reporter: was there a quid pro quo? >> there's so many more questions we don't know about the russian involvement in our election and the possible coordination of that involvement with people in the trump administration or close to the trump campaign. >> reporter: european diplomats say all this is frightening u.s. allies no longer certain that america has their back. putin is already flexing his muscles, tonight violating a 1987 nuclear treaty negotiated by ronald ray gain and mikhail gorbachev by deploying a cruise missile banned 30 years ago. lester? >> thank you. tonight members of congress from both parties are calling for an investigation of michael flynn and nbc news has learned the fbi questioned flynn shortly after president trump took office. we have late details from our justice correspondent, pete williams. >> reporter: just a few days after michael flynn became the

national security adviser, he was interviewed by fbi agents according to senior u.s. officials about his phone call with the russian ambassador. the officials say the interview was part of the fbi's long running investigation into russia's attempt to influence the presidential election including its hacking atacks on the democrats. flynn was not under investigation, the officials say, the russians were. although the white house said flynn was fired for misleading the vice president, two officials said the fbi agents didnot believe flynn lied to them, and do not expect to see any charges come out of that interview. >> good afternoon, everyone. >> reporter: but his days of answering questions are not over. members of congress who have launched their own investigation into russian meddling say they want to hear from him. >> it will be likely he will be asked to talk to the committee about post-election activities and any other activities that he would be aware of. >> reporter: some in congress say the transcripts of flynn's

phone call with the russian ambassador should be released. >> given the public was misled about these conversations, i think the public has a right to know what flynn represented and who he was speaking for. >> reporter: separately the army has been investigating whether general flynn >> chuck, where to begin here, this is less than a month into this administration. what are the biggest questions the white house needs to answer right now? >> i think there are a couple. why was vice president pence kept in the dark about this, not only was he misled by mike flynn which he admitted to but for him to be kept in the dark for over a week, nearly two weeks about what came over in the justice department, why is that significant? mike pence is the security blanket for a lot of congressional republicans. if it is somehow common knowledge on

capitol hill that mike pence is no the in the inner circle that is going to make some congressional republicans a bit more nervous and maybe a lot less friendly to this administration. i think that's a big one they need to clear up because of the conduct itself and politically in order to make sure their relationship with congressional republicans doesn't go south fast. >> all right, chuck todd, chuck, thanks. one last note on politics. the u.s. government ethics office is recommending that the white house investigate trump aide kellyanne conway and take discipline action against her after she made a public endorsement of ivanka trump's fashion line. a breach of ethics rules. now to northern california where an evacuation order has been lifted for communities below the tallest dam in the nation. crews are still scrambling to repair a hole in an emergency spillway which forced nearly 200,000 people to flee their homes. if the spill way to collapse, it could cause catastrophic flooding but the sheriff says that risk has been reduced,

allowing residents to return home. half way across the country in the meantime a line of severe storms brought at least three tornadoes touching down outside of houston with damage and a number of minor injuries reported. there's news in one of the most infamous kidnapping cases in american history. etan patz vanished in the streets of new york city in 1979. the little boy, one of the first faces of a missing child on a milk carton after a decades long mystery agonizing for his parents, his killer is brought to justice. here's nbc's stephanie gosk. >> i am truly relieved and i'll tell you it's about time. it really is. >> reporter: it was nearly four decades ago that stan and julie patz sent their 6-year-old son etan to the bus stop in new york by himself. >> he disappeared. >> reporter: they would never see him again. they found him guilty of kidnapping and second-degree murder.

>> this man is guilty of doing something really terrible so many years ago. >> reporter: the disappearance case gripped the country. in that predigital era authorities relied on missing posters to generate leads from the public as well as a brand new idea. etan patz was one of the first missing children to be profiled on the side of milk cartons. the street where etan has disappeared has changed a lot since 19 the. it was grittier then, and the crime rate was a lot higher, but as the streets cleaned up, the mystery continued to haunt new yorkers. a break in the case didn't come until 2012 when police got a tip from one of hernandez's relatives. hernandez was questioned and eventually confessed, telling police he lured etan into the basement of the corpser store where he worked. in a 2015 trial, the jury deadlocked but this time in new york supreme court, the verdict was unanimous, and hernandez faces life in prison. his defense attorney said he will file an appeal. etan patz's story no

less shocking all these years later is still not resolved. nbc news, stephanie gosk, new york. still ahead, the hollywood super star sparking an investigation with scare in the sky. what happened when actor harrison ford brought his private plane in for a landing? also a brazen assassination at the airport. did an infamous dictator have his own half brother killed?

tonight, nbc news has learned the faa is investigating a dangerous incident involving actor and pilot harrison ford, who was involved in what some have called a close call in southern california yesterday when ford mistook a taxi way for a runway flying right over the top of an american airlines jet. our aviation correspondent tom costello broke the story today and has our report. >> reporter: harrison ford may be best known for his acting, but he's also an accomplished pilot. tonight, though, the faa is investigating a serious and potentially dangerous incident yesterday involving ford and his single engine husbandry and an american airlines passenger plane in orange county, california. aviation sources tell nbc news ford has been cleared to land on the short runway at john wayne airport, runway 2-0 left but instead he lined up and landed on the parallel taxi way, c or charlie,

where planes taxi before takeoff. in the process he flew right over the top of an american airlines 737 that was holding at the end of the taxi way before preparing for departure. it was loaded with 110 passengers and six crew members for a flight to dallas. unclear if anybody on board knew what happened. once on the ground mr. ford radioed air traffic control, was that airliner meant to be underneath me? the controller told ford he hadn't landed on the runway, instead you landed on taxi way c, to which ford replied, i landed on c. landing on a taxi way is a clear faa violation. the question is, was ford distracted? >> unfortunately, we have seen this sort of thing before where somebody mistakenly identifies a taxi way for a runway. in this case the runway he was to land on was very narrow. >> reporter: it was just two years ago that ford was injured when his world war ii plane crashed on a san ma monica golf course. investigators blamed the crash on an engine

failure. tonight harrison ford is declining to comment. experts say he could receive a washing let are or have his pilot's license suspended, though that seems less likely. tom costello, nbc news, washington. we're back in a moment with a historic basketball feat that's never been accomplished until now.

we're back with an apparent assassination brazenly carried out at an international airport. the target? the estranged half brother of north korea's infamous leader. and it's raising suspicions that kim jong-un may have once again marked one of his own relatives for death. nbc's keir simmons now details. >> reporter: a cold-blooded execution straight from a spy movie local media reports say. north korean dictator kim jong-un's half brother, kim jong-nam apparently targeted by two female assassins. he'd criticized north korea's supreme leader. the staged hit at an airport in malaysia.

an unidentified woman covering his face with a cloth laced with liquid, police say. he was seen struggling for help and sought assistance from airport staff but died in an ambulance. north korea's ruthless ruler showing no mercy. kim jong-un had his own uncle put on trial and executed. kim jong-un's late's parent target, his father's son. kim jong-nam had been their father's favorite but in 2001 he was caught sneaking into japan with a false passport wanting to visit tokyo's disneyland. estranged from the family he questioned his brother's rule. a dangerous move. >> there still is resistance, there still is criticism. i think that's why we're seeing high level purging and murders like this. >> reporter: the alleged killing days after kim jong-un personally oversaw a new missile test clearly aimed at provoking president trump. north korea's dictator

demanding attention, and eliminating opponents, even family. keir is immobs, nbc news, seoul, south korea. switching gears now to say the least. congratulations are in order after a major milestone by one of the greatest sports dynasties of all time. the uconn women's basketball team won their 100th game in a row, a streak stretching over several years. it's the longest winning streak in division 1 college basketball history. congratulations to coach auremma and the squad. when we come back, a love story for the ages on this valentine's day. "nbc nightly news" is brought to you by pacific life, helping generations of families achieve long-term financial security for over 145 years. pack again in 24-hours.

==jess/vo== plu... this mily mid-air . president o the-s ... when what they did to get to the baa ==jess/next close== next. finally, tonight, on this valentine's day, a moving story of power and love. they found each other when they least expected. when this couple was confronted with an uncertain future, they decided to beat the odds together. our kerry sanders has their touching tale. >> reporter: this love story begins on a blind date. deborah bradley and gary gross each divorced and not looking for anything more than friendship. >> i surprised myself

when i found myself in love. >> reporter: that love would be tested when she was diagnosed with stage four pancreatic cancer, one of the deadliest. >> like everybody that hears the cancer word, you're terrified at first. >> reporter: the worst day of her life also became the best day. >> she looked at me and said, i don't think i can do this alone, and i said, you don't have to. you will never ever be alone. that's when i got down on my knee, and i said "will you marry me?" >> i said "what, today?" i said "what will i wear?" >> reporter: they quickly found a justice of the peace and pledged those vows in sickness and in health. after nine months of an experimental treatmentality emery winship cancer center, debra rang a bell to celebrate she's now cancer free.

doctors can't quantify love. i guess it doesn't show up on the scans, but what role did it play? >> oh, wow. >> huge. it's just huge. it's everything. love gives you hope when things are at their darkest. it gives you something to look forward to. >> reporter: now looking forward to a trip to paris. gary surprised debra on this holiday celebrating commitment to true love. >> oh, thank you. >> reporter: kerry sanders, nbc news, atlanta. >> that's going to do it for us on a tuesday night. i'm lester holt. for all you have for all of us at nbc news, thank you for watching. happy valentine's day and good night. happy runs=05

=ess/take voright now at 6: how happy are you to be home? >> man, you don't know. you don't know. >> right now at 6:00, reloaf in oroville. evacuees allowed to go home. but those flooding fears are still in place. the news at 6:00 starts right now. good evening, thanks for joining us, i'm jessica aguirre. >> and i'm raj mathai. within the past hour, president trump approving federal assistance for lake oroville and several bay areas. federal money will pay for the recu recue and the resource to help

fix. the evacuation order has been downgraded. they need to be ready to leave again if things go ba bad. water officials are drained enough of the lake so the emergency spillway will not be needed to handle runoff from the next storm which should arrive on thursday. if it's needed, crews are needing what you're seeing here, helicopter to place the bolder ons the emergency spillway to cover up the erosion that popped up last weekend. let's begin with mark matthews in downtown oroville which ismeis coming back to life. >> reporter: you can see behind me downtown oroville still pretty quiet on this valentine's evening, but there are cars on the street and there are signs of life. the town of oroville emptied out this weekend as the river rose. holes