♪ this is "nightline." >> tonight, fair play? the latest battleground in elite sports. >> what struck me about it most is just the visceral anger that seems to come through. >> controversy in the swimming world. all eyes on trans athlete leah thomas, shattering records. why some say trans female athletes have an unfair advantage. >> men and women are built very differently. so we created women's sports specifically so that biological women have a place to win. >> even caitlyn jenner speaking out. >> biological boys should not play in women's sports. >> but how should the rules be changed? >> the trans athletes that i

know ae athletes. a true athlete always wants to make sure that a competition is fair. plus crisis in ukraine. with war now seemingly almost inevitable. >> my sense, it will happen in the next several days. >> u.s. diplomats warning about the impending disaster. >> russian missiles and bombs will drop across ukraine. cyber attacks will shut down key ukrainian institutions. >> the u.s. saying russia is still moving forces toward the potential battle zone.

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♪ good evening. thank you for joining us. how should trans athletes be allowed to compete at the highest levels of elite sports? that controversy has dominated women's swimming for months and is reigniting this week with trans female swimmer leah thomas tearing up the competition at the ivy league women's championships. here's my "nightline" coanchor juju chang. >> i love the feeling of racing. and just being in the water action for me it's not even about the winning, it's about the racing. >> reporter: powerful. fearless. isaac hennig fell in love with swimming at the age of 4. >> it's about the community, it's about the friendships that you build.

>> reporter: being a swimmer defines him. the yale swim team, a place of belonging for the college junior. but outside the pool, isaac, who is assigned female at birth, was struggling. >> it's a constant performance. it's exhausting. >> there were moments where you thought about hurting yourself? >> yeah. those were some of my lowest moments. and some of it was the struggles of living a life where all of the decisions you're making feel like they're going against yourself. >> what was it like to come out to your team? >> i was scared. i'm going to be honest. i was nervous. i wasn't sure how they were going to take it. >> reporter: isaac says it was relief to find his teammates more than welcoming. >> isaac's a happy person. always has been. a little smile, a little charm. and i didn't like to see, you know, this dynamic person not happy.

>> reporter: eye san beg >> reporter: isaac began socially transitioning, undergoing top surgery. he exceeded to compete for the women's team. >> the big thing i decided not to do is start hormones. i felt attached to the team at yale, and i wanted to complete what i signed up for. >> reporter: for other athletes, especially women, the line between sport is tricky. all this fueling a national debate how to be inclusive to trans athletes while balancing what some argue is fairness. >> i think what struck me about it most is just the visceral anger that seems to come through in a way that, for me, doesn't really feel justified. you know, i'm really just some guy out here swimming within my life, and i don't think that anyone deserves that level of anger. >> reporter: isaac finding himself front and center, making waves during a head-to-head competition with one of the most controversial college swimmers, leah thomas, a transgender woman

assigned male at birth. leah's record-shattering performances, a lightning rod in the debate over trans women competing in elite athletics. >> from the beginning, i've said that biological boys should not play in women's sports. >> we all should feel comfortable with who we are in our own skin. but i think sports should all be played at an even playing field. >> reporter: leah swam for u-penn's men's team for three seasons. she's now qualified to compete on the women's team after undergoing more than two years of hormone therapy. she declined to speak with us but roipecently shared her experience on a podcast. >> i've experienced a lot of muscle loss and strength loss. i have to, like, readjust my goals and what i think of as a good time or a good pace to hold practice. >> reporter: in two events this season, leah posted the fastest times in women's college history. but instead of celebration, it was met with outrage.

what do you make of that argument, that leah thomas as a trans woman should not be competing against other women? >> i think that a lot of the very strong takes come from people, you know, misunderstanding what it means for leah to be complying with the rules, to have undertaken all of these steps to ensure that things are fair. >> reporter: isaac beat leah in the water by almost 2 seconds back in january. >> hennig had the fastest time out of everybody -- >> reporter: then lost to her by a hair during last night's ivy league championship. >> leah thomas making up a lot of ground. >> reporter: still, some argue that the physical advantages of going through male puberty gives trans female athletes an unfair advantage, even after years of hormone therapy. >> leah thomas has been through puberty. so that's ten years of having testosterone, making broader shoulders, bigger lungs. >> reporter: nancy is a women's rights attorney and former three-time olympic gold swimmer. she founded "champion women"

which advocates for girls and women's equality in sports. >> men and women are built very differently. so we created women's sports specifically so that biological women have a place to win, to getting a get accolades. >> reporter: she created a petition, arguing that leah is taking away some of their chances to compete. >> they want her to lead a happy, productive life, but they don't think it's fair that she's competing in the women's category. that's not trans hate. >> why do you think the swimmers didn't want to reveal their identities? >> the swimmers did not want to or could not reveal their identities because they were threatened with getting kicked off the team and possibly getting kicked out of school. >> reporter: the controversy over leah thomas having ripple effects in the sporting world. >> i think the evidence based on her times alone, and the fact

that she's gone there being a medium-rank male swim tore a top-ranked female swimmer, makes us think that perhaps she retains an advantage. and that brings all fairness questions into play. and whether a year is long enough, whether any duration of time is long enough. >> reporter: at the beginning of the season, the ncaa policy required a year of estrogen or testosterone suppression for transgender athletes to be eligible to compete. but last month in the middle of the season, they changed course, allowing each sport to set its own rules. so usa swimming did just that. this month announcing new guidelines for trans female athletes, requiring a lower level of testosterone and adding an independent three-person medical panel to determine whether or not the athlete has unfair competitive advantage. there's been a lot of controversy and opposition to that rule change. what do you think about that? >> my priority is always going to be inclusion in sport.

what it comes down for, for me, is the trans athletes that i know are athletes. and at their core, a true athlete always wants to make sure that a competition is fair. >> there are also a lot of people who think it's leah's success that's creating this push to change the rules. >> that does feel like a, you know, very quick connection, to me. she's being successful at our sport. and all of a sudden the rules are being changed. >> reporter: but these changes come after continued scientific study that questions whether someone who's gone through male puberty can fairly roll back enough of the physical advantages they may have gotten. >> i think you have to ask yourself about the legacy effects of tells is to treassto. somebody that's been exposed to high levels of testosterone for six, eight years, what does that do even as the testosterone goes away in transition? >> is it fair to say you can't reverse the effects of legacy

testosterone? >> it would be difficult in all facets. for example, lung volume is not going to get smaller. procedural things relating to bone structure and bone density aren't going to be different. people's hands and feet probably aren't going to get smaller. >> we talked to a number of people who were in the medical world, and they were pointing to things like, once you go through puberty as a man, you have bigger lung capacity, you have more muscle strength. people are convinced almost no matter what you say that that would give a trans woman an advantage. >> i think one of the things that i always come back to is, an athlete like michael phelps, who we can all point to, and say, yeah, he has twice the lung capacity of any one of his competitors. but no one was upset or calling it unfair. if you're going to point to those things, then your conclusion has to be, well, yeah, they were built to do sport. you know, they were built to swim. it's not about puberty. because anyone can go through any sort of hormonal change and still not be a great athlete because there is just so much more to great athletes than

hormones. >> reporter: the ncaa announced last week that the new usa swimming guidelines would not be enforced this year, clearing the way for leah to compete in her final year. >> unfortunately, it has become about leah thomas. and that is a tragedy. because it never should have. we have so many sport leaders that are paid exceptionally well to be able to come up with sports policy. but they weren't going to do that until we had somebody like leah thomas coming forward. >> reporter: isaac says his transition has been liberating, allowing him to become a better version of himself. and what's it like when you catch a glimpse of yourself? what strikes you? >> i joke about it with my friends a lot. but i've just become so much more self-centered. i've checked myself out in the mirror, you know. >> liking what you see? >> exactly. you know, there's something

really powerful about being able to, you know, look at yourself in the mirror, if a reflection, say, yeah, that is me. and i love it. >> in some ways, you're swimming better than you ever have. you're breaking your own personal bests. >> i love the saying, a happy thinkm just at my core so much happier, so much lighter, than i was before. >> our thanks to juju. up next, ukrainians are preparing for russian invasion. what's on the horizon? are you tired of washing dishes? well flip the way you clean'em. introducing dawn platinum ez-squeeze. it's a new, upside-down bottle... with no cap. you just grab and squeeze. platinum's upgraded, more powerful formula breaks down and removes grease 4 times faster. nice! no flip, no mess. platinum is also a go-to grease cleaner for your sink, your countertops, and to pre-treat stains on laundry. faster. easier.

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tensions between ukraine and russia are escalating with war now seeming to be a foregone conclusion. president biden today saying russian forces appear to be moving closer to potential targets and that he senses a russian invasion will come in the next few days. even though russia claims that its forces are returning to their bases. secretary blinken was even more blunt. at the u.n. warning the russian attack would include bombs and missiles and cyber attacks on the country's infrastructure and institutions. earlier this morning, a school in eastern ukraine came under artillery fire and what may have been the genesis for a false flag operation. are we now on the brink of a major conflict? earlier i spoke to general robert abrams, former commander of the u.s. army forces command, and elizabeth neumann, a former homeland security official. general, i'd like to start with you. secretary of state blinken told the u.n. security council today that russia was preparing to

launch an attack in the coming days, bluntly saying a combination of bombs, tanks, soldiers, and cyber attacks could cause havoc across ukraine. can you explain how lethal the plans sound? >> the russian military, highly modernized. and president putin has postured about half his force, somewhere in the 130,000 to 150,000 troops level, on three sides of ukraine. so from the east, from the south, and from the north, with troops stationed in belarus. this is a highly capable, highly lethal formation. so if there is a ground invasion of ukraine, in one or more places, we're going to see massive destruction, massive loss of life, and a huge number of displaced ukrainian citizens trying to get out of harm's way. so this is a very dangerous place to be in right now.

>> sobering. elizabeth, next question to you. ukraine has reported cyber attacks on the websites of several government entities and major banks. what do you know about these attacks, and given russian history and expertise in this area, what damage do you expect they can do to ukrainian agencies? >> well, i think what we've seen this week is just the tip of the iceberg and not to diminish what the ukrainian officials have described as some of the worst attacks that they've experienced, but it's certainly not the worst that can come. i think we're likely to see attacks that would render certain capabilities, certain crucial capabilities, like command and control, communications, internet. in the past we've seen electricity being able to be turned out through cyber means. so all of those would likely be triggered just before kinetic military actions start to happen. it creates chaos on the ground.

it makes it harder for ukraine and for any allied support to figure out what's going on, how to best help them. >> general, russian officials claim that military resources are being moved back to their bases. but u.s. intelligence says more than 7,000 russian troops moved to the border yesterday. what's the big-picture explanation for all of this tit for tat foss toposturing? >> we all know president putin is the master of deception. he's done this many times before. he's well schooled in it, well trained in it. for them to say that they have withdrawn a certain number of forces, you could say that another way. he could have pulled back 7,000 troops to reposition them to another part of the ukrainian/russian border, to be able to mass appropriate amount of combat power to achieve a penetration. so when we see u.s. officials and others say, hey, we've seen

no evidence of this, what one man's temporary withdrawal to reposition is another man's view of, hey, nothing's changed, and in fact, there's been reinforcement. so it's much more than semantics. >> elizabeth, final question. administration officials are saying russia could use a false flag attack as a pretext for invasion. what signs are you looking for from intelligence officials in terms of an imminent invasion on the ground? >> well, i think we may have already seen some of that start. we saw today that the russians are claiming that there are mass graves in ukraine. they claim that they've been investigating this for eight years and they finally put together a report that they have turned over to the u.n. today, claiming that there's been genocide. putin actually used those terms today. this appears to be part of their justification for why military

action might be needed. nobody else is believing what putin is saying. but he's trying to come up with that excuse, that he can tell his domestic audience why he needs to put men and women in harm's way going into ukraine. so i think we're already seeing some of it. we were told by members of the biden administration that we might also expect to see chemical attacks or rumors of chemical attacks. we saw a kindergarten shelled today. so there are a number of little provocations and propaganda that is starting to come out. i think the playbook is under way. i think it's a matter of time before we see kinetic action. >> anxious times. we'll depend on your expertise in the days to come. thank you both. >> thanks for having me. >> thank you. up next, the controversial 15-year-old russian skater. her final performance in beijing was not medal caliber. is now a good time for a flare-up? enough, crohn's!

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♪ finally tonight, the russian skating sensation at the center of an international doping investigation, camillaville yaif

have a. the figure skater favored to win and entering the day leading the competition fell several times and ended with a fourth-place finish at the beijing games. the 15-year-old tested positive for a banned substance but was still allowed to compete, left the ice in tears. that's "nightline" for this evening. you can catch our full episodes on hulu. we'll see you right back here same time tomorrow. thanks for the company, america. good night.