The video summit between President Joe Biden and Vladimir Putin didn’t resolve the most dangerous foreign-policy crisis so far for the Biden presidency: Can the United States and its NATO partners prevent Russia from taking over Ukraine by force?

Amazingly, no one is yet certain whether Putin has massed nearly 100,000 Russian troops on three borders of Ukraine with the intent to invade – or whether he is using them to pressure the West into consigning that country to Russian domination.

“We still do not believe President Putin has made a decision,” National Security Adviser Jake Sullivan told reporters after the video call Tuesday.

But the fact that the video call was held on Dec. 7 – the anniversary of the Japanese attack on Pearl Harbor – is truly symbolic. If Putin can take control of a European country by threatening or using force, it will erase the principles of international conduct that have kept peace in Europe since World War II. “The international system will be set back decades,” Adm. James Stavridis told MSNBC.

» READ MORE: Putin's salami war in Ukraine destabilizes democracies I Trudy Rubin

China would certainly take keen notice in deciding whether to move on Taiwan. And NATO’s remaining cachet, following on the chaotic withdrawal from Afghanistan, would be gone.

This geopolitical game of chicken will probably play out in the next few weeks, when the number of Russian troops on Ukraine’s border is expected to rise to at least 175,000.

Europe’s future depends on whether Biden and European allies can convince Putin the cost of an invasion would be too high.

However, Putin’s psyche is a particular part of the problem. The Russian leader has manufactured this crisis out of personal paranoia and unappeased anger over the collapse of the Soviet Union. He insists the West wants to use Ukraine as a “springboard against Russia.”

This mentality was behind Russia’s invasion and annexation of the Crimean peninsula in 2014. It also drove the Kremlin’s effective annexation of the Donbas region in eastern Ukraine by using pro-Russian Ukrainian proxies it armed and trained.

Now Putin wants a legal guarantee that Ukraine will never become a member of NATO. (Biden has rightly ruled out this Kremlin effort to control NATO — or sovereign Ukrainian — decisions.)

In fact, NATO has no interest in having Kyiv as a full member in the foreseeable future, nor in deploying weapons systems to Ukraine that would target Moscow, a threat about which Putin openly fantasizes. What the Kremlin leader refuses to see is that increased NATO support for its current eastern European members is precisely because the Kremlin threatens force to achieve its aims.

Indeed, Putin has made clear he believes Ukraine has no right to be a separate country. “We are one people,” the Russian leader wrote in July, in a lengthy screed laying out “the historical unity of Russians and Ukrainians.”

In tense talks, Biden warned Putin that an invasion of Ukraine would trigger massive economic penalties that go well beyond the sanctions imposed after the invasion of Crimea. The new penalties could block Russian companies from capital markets and target Russia’s economic elite. Most drastic, they could even cut Russia off from the global financial system, called SWIFT, that enables international money transfers.

Sullivan also made clear that the administration would finally work to block activation of the Nord Stream 2 pipeline intended to bring gas from Russia to Germany. “If Vladimir Putin wants to see gas flow through that pipeline, he may not want to take the risk of invading Ukraine,” the security adviser said.

Yet all these economic penalties are geared to blocking a full-scale invasion. It is not clear whether NATO members will stand together firmly if Putin mounts a lesser incursion — say, to link Russia by land with Crimea by seizing another chunk of Ukraine.

Nor is it clear whether the Europeans will split with the White House if Putin’s price is the consignment of Ukraine to formal Russian overlordship. That would mark a 21st-century repeat of the infamous Yalta Conference in 1945, where Joseph Stalin and President Franklin Roosevelt agreed to Russian domination of Eastern Europe.

“I believe Putin’s intention is to extort concessions,” John Herbst, the former U.S. ambassador to Ukraine, told me. “He is hoping the White House will be weak-kneed, or Brussels, or Germany, or Ukraine.”

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That analysis makes sense when I recall my weeks in Ukraine in 2014 after Russian proxies fomented violence in the Donbas. At the time, Russia was reportedly planning to seize all of southern Ukraine – where Russian speakers predominate. But as I heard when traversing that territory, most Russian-speaking Ukrainians had no desire to be ruled by Moscow and would have put up a hard fight.

The Ukrainian army is far better armed and trained now, and Putin is likely reluctant to take heavy casualties. But, after all this drama, he is also unlikely to do nothing.

So the real test for Biden and European leaders is whether they can hold together on truly tough sanctions if Putin avoids a mass invasion but bites off another piece of Ukraine. “Or whether Putin persuades the West to squeeze Ukraine’s leaders into accepting a role as a Russian satellite.

Eastern European members of NATO are already expressing fears that Biden will make concessions.

“This is a moment of truth for NATO,” I was told by Alexander Vershbow, the former deputy secretary-general of the organization. And for Biden as well.