it was shot that inside the building when nicholas mamer died.his distinctive light blue building, once a daycare center. in the distance, the spire of a partially destroyed church. here are all three locations seen from above. after nine months of slow, brutal fighting, nicholas mamer had found himself in the midst of a fierce, fast onslaught. >> nick wasn't with them when they withdrew from the building, and they were trying to recover -- do a recovery operation when it was, you know, reoccupied by the russians. so they weren't able to do it. >> then wagner got there first? >> wagner got there first. >> reporter: clare sebastian, cnn, london. >>> a blunt warning from the leader of russia's wagner mercenaries who says the kremlin will face major blowback if it doesn't turn things around in ukraine. yevgeny prigozhin spoke with a russian blogger. that blogger was fired after the interview. among other things, prigozhin said moscow must escalate the war to avoid being bogged down in even more costly conflict. otherwise, he said an unsettling part

>> this was nicholas mamer, retired special forces soldier. he'd been rein for more than a year doing humanitarian work. in particular involved in training the ukrainian territorial defense forces. and we believe he was with them in bakhmut. and the story of how he died really runs now concurrently with the leadup to russia's claim which happened a week ago today to have taken all of bakhmut. that is something that ukraine still disputes. they say they're still defending a very small pocket of the town on the western edge. but as we looked at how he died, obviously this comes after nine months of very slow fighting over a city that frankly it would take in peace time 15 minutes to drive from the eastern edge to the western edge of that city. so you see the amount of territory we're talking about. but as we look into the circumstances of his death it really helped us build up a picture of the battles for those final pieces of land that fell into russian territory. have a look. >> translator: under cover of darkness a russian military blogger fi

grainy video but purported to show an american victim identified as idaho native nicholas mamer. was trapped in a building hit by rush artillery fire. now they're trying to get her body out of the war zone to give him a proper military burial which they say he deserves. trace, he said earlier that he felt he needed to help ukrainians uphold democracy. his uncle said he was trying to do good for the world. he's tenth american killed in war. back to you. >> trace: ten americans. do we have numbers on roughly how many americans are in ukraine helping this effort? >> we don't have a good calibration on that. i'd say in the thousands. i have met with a few. yeah, they're there for a purpose. they want to help out formally. the u.s. do not have boots on the ground in ukraine, but these are informal boots. people who are caring about what is happening over there. they're brave, they're fighting and getting injured and getting killed just like the ukrainians there are too in big numbers. back to you. >> trace: yeah. it's interesting. greg palkot live for us in london. thanks, greg. meant

retired army staff sergeant nicholas mamer died in a brash of russian artillery fire in the embattledity of bakhmut. he was working for the nonprofit afg free in ukraine. idaho senator jim rich said he met with mamer in kyiv last summer, saying, quote, it was clear nick was exceptionally well trained for and sober about the realities of the war in ukraine. cnn's nic robertson joins us now from eastern ukraine. nic, the sergeant was in bakhmut when he died. we keep getting reports of fierce fighting there, including more movement that we've heard in months and months with ukrainians perhaps taking back territory. what are you learning? >> reporter: yeah, there's two fights going on in and around bakhmut at the moment, there's the one in the center, the fight for high-rise buildings where the russians continue to take territory where we understand that intense fight there was where sergeant maimer finally was killed in the fighting, and then there's the fight around the outside and the fields to try to sort of encircle the city. it's in the fields and around the city the nuke yan govern

we have learned that nicholas mamer is one of at least ten americans to have died in the ukraine sincehe start of the war. this as the chris christies say they have the momentum around that eastern city of bakhmut >> reporter: this morning, the grim confirmation that another american has died fighting in christie overnight, nicholas's aunt confirmed the 45-year-old veteran from boise, idaho, passed away. yesterday a video shows the wagner mercenary chief prigozhin standing over what he says is a dead american soldier in bakhmut. the group posting an idaho driver's license and what appear to be genuine documents for him. the u.s. state department said they were aware of the report but offer nod official confirmation his family says he was a decorated veteran, his service record on tand by nbc news shows he joined the u.s. army in 1996. he traveled to christie in 2022, posting this update. >> and i'm putting together a training program for the territorial defense. that is going to allow me to hopefully save some lives. >> reporter: the fiercest fighting today over the ruins of what was o

just months before nicholas mamer died, he spoke with raf sanchez while training volunteer soldiers outsidekyiv. >> these people want the exact same thing that your average american wants. they want to, you know, raise a family, enjoy life, have a good quality of life, and have the chance for prosperity, a better future for their kids. >> reporter: his close friend, ken cobberline sharing more about the 45-year-old veteran. >> nick was probably one of the most selfless people i have ever met. he had a beautiful, bright life that unfortunately -- unfortunately he's not here anymore. >> reporter: now, as russia's air campaign is stepped up, at top of president zelenskyy's list is still american f-16 fighter jets. germany and the uk have said that any decision to provide jets or any assistance has got to go to the white house. and you have to believe that will be a discussion point in japan. >> molly hunter for us in ukraine. molly, thank you. >>> let's switch gears and go to the nba playoffs. the miami heat defying the odds makers. they shocked the boston celtics last night in game one of the

overnight nicholas mamers aunt, the 45-year-old veteran from boise, idaho, passed away.nding over a dead american soldier in bakhmut, posting a driver's license and what appeared to be genuine u.s. documents for nicholas maimer. the u.s. state department said they were aware of the report but offered no confirmation. he was a decorated veteran, his service record shows he joined the u.s. army in 1996. maimer traveled to ukraine in 2022 posting this update. >> and i'm putting together a training program for the territorial defense and that is going to allow me to hopefully save some lives. >> reporter: the fiercest fighting today over the ruins of what was once the eastern city of bakhmut. the ukrainians say they have recaptured nearly eight square miles in the last few days. overnight president zelenskyy trying to capitalize on the momentum with european allies. >> and that we in unity will give 100% in any field when we have a goal to protect our people and our europe. >> reporter: meanwhile, as the fighting shows no sign of letting up, the cia sensing an opportunity in