The looming threat of a new Russian military invasion of Ukraine has set the world on edge, with intense diplomatic maneuvering by the Biden administration and its European allies so far failing to bring Moscow off its war footing.

For months, Russia has been amassing troops and matériel near its borders with Ukraine, with some units arriving from as far away as Siberia. Russia also recently initiated large-scale military drills with its ally Belarus, which shares a border with Ukraine close to the Ukrainian capital, Kyiv. Over 100,000 Russian troops now surround Ukraine.

Though Russia announced that it was pulling back some troops from the Ukraine border, President Biden said on Tuesday that the United States has not independently verified Moscow’s claims, and emphasized that a new Russian incursion is “still very much a possibility.”

This is not the first time Russia, under President Vladimir Putin, has threatened Ukraine’s sovereignty. In 2014, Russia invaded, and subsequently annexed, Ukraine’s strategically located Crimean Peninsula and fomented an insurgency in Ukraine’s eastern Donbass region, which breakaway pro-Russian forces still retain partial control of to this day.

Given the high costs of a Russian invasion — experts believe it will be a bloody conflict that will isolate Moscow diplomatically and economically — many Americans are wondering why Putin would opt to launch a new incursion.

Yahoo News talked to some leading experts who have worked in U.S. intelligence and national security to get their assessments of Putin’s motivation for potentially launching this new invasion, and the wider politics of Russia and the region.

These former officials offered a diverse set of explanations for Putin’s motivations in Ukraine. Some see his actions as a bald play for regional dominance or power; others view them as springing from a desire to recapture territory lost at the end of the Cold War or from a desire to reconstitute the Russian empire. Still others look at Putin’s actions as a response to his fears — rational or not — of NATO encroachment, or of being toppled in a popular revolution that could lead to a trip to the gallows.

Interviews have been condensed and edited for clarity.

‘A KGB man’

Greg Sims, former CIA chief of station with Europe experience

I can’t imagine Putin really wants to invade. He’s a KGB man who feels more comfortable with subterfuge than brute military force. It’s a sign of his frustration that it’s come to this. He’s tried electoral manipulation, corrupt entanglement, economic pressure, and finally, disguised military attacks.

Each step was more manipulative than the last. A truly independent Ukraine was never an option for him, and now he’s left with just three choices: Grab Ukraine outright, lop off big chunks — almost out of spite — or give it up. He has to blame himself for this dilemma, because the one thing he didn’t try was being a good neighbor.

‘He wants to reassert Russia’

Ronald Marks, former CIA officer with experience on Russia issues

Putin is a throwback; the ten-dollar term is revanchist. But what he reminds me of, there was a Roman emperor called Justinian, after the Roman Empire fell in the west. And Justinian got in his head, this was about 100 years after, he was going to retake the Roman Empire. It was really costly; there was a plague. That’s sort of what Putin’s got in his head — he wants to reassert Russia, but he can only sort of afford so much.

And he will show his power internally. His constituency is inside, and he will have to start leaving a legacy at this point. And I think the legacy is part of it with him. He wants to be known as the guy who reconstituted and to some extent pushed Russia forward in the world.

I have seen him do nothing at this point that isn’t perfectly logical by what he would want to do. He is in a lot of ways the world’s meanest teenager. He really knows how to push buttons, and he also knows how far he can go. A teenager wouldn’t necessarily know that, but he does know how far to go.

Fear of the ‘Gadhafi scenario’

Michael van Landingham, former CIA Russia analyst

I think that [Putin’s current actions] relate essentially to Libya and the Arab Spring — and the election of [Barack] Obama. So Obama is elected on an antiwar platform, he’s an antiwar candidate, he’s elected in part because he proposes a reset with Russia. That reset materializes in some part with Putin’s handpicked successor, Dmitry Medvedev. But when the Arab Spring happens, Putin and his more conspiratorial advisers who have taken greater prominence in the past decade — the people who are heads of the SVR [Russia’s main nonmilitary foreign intelligence agency], FSB [a Russian intelligence agency that is the primary successor to the Soviet KGB], the Russian Security Council — those guys are real hard-liners, and really believe that the U.S., if left unchecked, would try to dismantle Russia and take Siberia away, drive Russia back to Moscow.

So Putin saw what he thought was a return to the pattern of the U.S. taking advantage of Russia — which basically means forcing policy priorities that Russia has to accept. And nowhere was this more true than with Russia’s 2011 abstention on U.N. Security Council resolutions 1973 and 1975, the U.N. no-fly zone on Libya and sanctions on Libya, where Russia could have vetoed it. And that set a precedent not only for NATO operations in a state that wasn’t threatening them, but a state that had given up a weapons of mass destruction program, a state that had pretty significant ties to Europe at that time.

[Libyan leader Moammar] Gadhafi kind of was an avatar for Putin’s animalistic fears of being shot in a ditch, which happened to Gadhafi. And it came during the presidency of an ostensibly antiwar liberal, but whose policy inner circle was staffed by people who thought democracy promotion and preventing deaths in the name of human rights was worth humanitarian intervention, people like Samantha Power and Susan Rice.

So Putin, who had had these concerns in the early 2000s, was essentially convinced by this. The U.S. couldn’t help itself. It didn’t matter if it was a Republican in power, a sort of neoconservative who wanted to advance the freedom agenda, or a Democrat who wanted to advance human rights. The United States would use military force to unseat autocratic governments if there was a popular uprising against them. And Libya was the template for Putin and for hard-liners.

We knew his goal was to make Ukraine ineligible for NATO membership by taking a part of it [because it would be impossible to admit a new member-state while it was already in an armed conflict with Russia]. But the really, really hard-liners — not the people quite in Putin’s inner circle but the people who influenced the people in his inner circle — were advocating for stuff like taking all of eastern Ukraine, going all the way to Odessa, all the way to Transnistria [a Russian-aligned breakaway republic in Moldova, west of Ukraine].

The only way you can get the policy objective that Russia wants — a defenseless Ukraine that Russia can have any veto over foreign policy over — is with Russian force. And in 2015 they got Minsk II [a diplomatic agreement that attempted to lay out a framework to end the war in the territories in eastern Ukraine held by pro-Russian separatists], which they thought might be implemented. But in taking Crimea, which was the most Russian part of Ukraine, and eastern Ukraine, which were also the most pro-Russian parts, making war on a fraternal Slavic nation, they pushed Ukraine further into the Western camp, because Putin was killing Ukrainians.

Why not [invade Ukraine] now? Because everything will be harder in the future. He’s got a million people in his country who died from COVID, and he’s facing reelection in 2024. And this is his new election with the new constitution that allows him to run again for a six-year term, so his first unconstitutional term [according to the previous legal framework].

He cares about security. If your goal is to have your state not invaded by the West, and not have a nuclear war with the West, and not get shot in a ditch, you’re willing to do a lot more than the next person for your regime’s security. And that’s his goal: to not get shot in a ditch.

And a lot of people would be like, “How could anyone think that could happen to them?” It happened to Mussolini, it happened to Ceausescu. Sic semper tyrannis.

‘Burn down their house’

Dan Hoffman, former CIA Moscow chief of station

First of all, NATO membership is a fig leaf. It’s a red herring. Everyone knows Ukraine isn’t joining NATO anytime soon. It takes unanimous consent; France and Germany won’t give that. Putin uses that as a convenient way to frame the narrative for his disinformation propaganda. NATO is a defensive alliance but it represents everything that scares him.

What he’s trying to do to Ukraine isn’t deny them NATO membership; it’s more broad than that. He’s trying to break Ukraine’s links to the West.

He’s doing it in three ways: economically, going back to the NotPetya attack [a catastrophic 2015 cyberattack on Ukrainian businesses and infrastructure], which was designed to make Ukraine an inhospitable place for commerce, and right now you’ve got capital flight, the risk of war, all those things. Ukraine is not a great investment.

No. 2, he’s trying to destabilize Ukraine politically, internally. So [Ukrainian President Volodymyr] Zelensky is struggling through the worst poll numbers of his term, and Putin wants to show that your elected leader isn’t up to the task of dealing with the threat from Russia.

The third thing he’s doing is trying to use Donbass to exercise a veto over Ukraine’s foreign policy. And that’s where we get to what he’s doing right now, which is extorting the United States and the West by putting out 130,000 troops, military exercises in Belarus, militarizing the Black Sea with 11 amphibious ships and submarines — all of that designed to drive up the tensions and induce us to make concessions.

He’s made zero concessions, by the way. Nothing. We’ve offered to restart arms control negotiations, we’ve offered to give him access to the Aegis air defense in Poland and Romania, the Ukrainian ambassador to London had to walk back on not joining NATO even though it’s in their constitution, we’re offering, offering, offering, and Russia says, “We need more from you.”

‘Just a damn bully’

Chris Miller, former acting secretary of defense, 2020-2021

Putin’s motivation: It’s the big unknown, but I don’t think it’s that difficult. Putin’s just a damn bully, and everything you need to know about Putin, if you’ve spent any time at a junior high school playground, it’s familiar to you. I do think it’s deep-seated in his psyche; I don’t think it’s deep-seated in the Russian psyche. People want to make it out to be, “They need a land corridor to their warm water port.” [That is, that the Russians might seek to invade and occupy the portion of Ukraine that would connect Russia via land to Crimea, which Moscow annexed in 2014 and which contains a critical Russian naval base and port on the Black Sea.] That’s clichéd. Let’s be honest, there’s got to be a domestic political calculation as well.

And there’s that geostrategic element where he’s like, I’m pushing, and they’re not pushing back, they’re just talking a good game. I think he’s just going to keep pushing until someone stands up against him, just like the playground bully. It’s playground bully 101.

I’m sure he’s sitting there saying, ‘I can’t believe that they’re letting me get away with this s***.’ The U.S. leadership’s just been feckless. And he got to be saying, ‘Holy crap, I can’t believe this.’ He’s like, ‘I think I’m going to pull this off.’

‘A desperate attempt to win back the empire’

Paul Zalucky, a former senior CIA official who served in Kyiv and Warsaw

This is why he might go in: because without Kyiv being a Russian city (because they always insist it’s their history, though it’s not), Russia ceases to exist as a global power. It’s just another country, and when you look at their [gross domestic product], which is less than Italy’s, they have nothing except nuclear weapons. And they can eat those if they want them.

The one factor that argues for him going in full-scale like this is it’s a desperate attempt to win back the empire, not so much the Soviet Union, but the Russian Empire, what Peter the Great had. And I think the Baltics are also part of that mission, but not right away.

‘Putin has pushed twice with no real consequence’

Josh Manning, a former Russia military and foreign policy analyst with U.S. European Command

Back in 2008, a few of us saw the Russian incursion into Georgia coming. You had two bullies going at each other for many months beforehand and Georgian President Mikheil Saakashvili was really pushing his luck. He thought the U.S. would be there to help his overreach, and we did not. Should we have? At the time I didn’t think so, though the consequences for the incursion should have been far more severe. But Iraq, and by then to a lesser degree Afghanistan, were the focus for the U.S. then.

Then in 2014 was a small incursion into Ukraine. Same goals as Georgia and same achieved result. Again, the focus was the Middle East [now Yemen and the Horn of Africa], so Russia-related problems weren’t a major focus or priority.

So Putin has pushed twice with no real consequence and he actually emerged stronger from both events.