The best path on Russia-Ukraine

To confront Kremlin aggression, Ukrainian President Volodymyr Zelensky declared Tuesday a "day of unity."

To achieve the same objective, President Joe Biden has galvanized a new era of unity among NATO allies and partners. While the solidarity may not prevent a Russian invasion, it has so far clearly communicated a consistent message to Russian President Vladimir Putin about the military, diplomatic and economic cost of any incursion.

And the NATO support has reassured Zelensky that Ukraine, like all sovereign nations, has a right to determine its own military and diplomatic direction.

The Western alliance, Biden said in an address to the U.S. on Tuesday, "is as unified and determined as it has ever been. And the source of our unbreakable strength continues to be the power, resilience and universal appeal of our shared democratic values.

"Because this is about more than just Russia and Ukraine; it's about standing for what we believe in, for the future we want for our world, for liberty," Biden continued. "The right of countless countries to choose their own destiny, and the right of people to determine their own futures, for the principle that a country can't change its neighbor's borders by force. That's our vision. And toward that end, I'm confident that vision, that freedom will prevail."

Perhaps it's begun to. Putin signaled a desire for diplomacy to continue, as well as a slight withdrawal of some forces. But Biden as well as NATO Secretary-General Jens Stoltenberg and independent military analysts have indicated that there is no evidence yet to back those claims, and in fact the opposite may be true.

Biden said that Russian forces "remain very much in a threatening position" and that more than 150,000 troops (higher than previous estimates) are encircling Ukraine along its eastern and southern border and from Belarus to the north. What's more, Ukraine suffered a significant cyberattack on Tuesday, with experts suggesting Russia was the likely culprit.

Biden reiterated that because Ukraine is not a NATO nation, U.S. troops will not fight in the event of an invasion. But the U.S. and several other alliance members have sent materiel to Ukraine to aid in its self-defense. Additionally, NATO has deployed more forces — including some Americans — to front-line nations in order to deter any possible Putin moves beyond Ukraine. "Article 5," Biden said, referring to the collective-defense clause of the pact, "is sacrosanct."

Michele Flournoy, former undersecretary of defense for policy during the Obama administration, said during a Wilson Center virtual event on Tuesday that in some sense Putin has exacerbated "one of his greatest fears" — a "strong NATO with a strong military posture in the front-line states of the Baltics and Poland and Romania, and so forth. And the irony of this crisis that he's manufactured is he has actually pulled NATO together, reinvigorated its sense of purpose and importance and buy-in across the board and will create a more robust NATO posture facing Russia. So he's managed to create his own nightmare in pursuing this course of action."

The revitalization of NATO comes after frequent disdain for the alliance from former President Donald Trump — and after Biden failed to fully consider the perspectives of allies in executing the U.S. withdrawal from Afghanistan. Biden, who ran as an experienced statesman, should not have had to learn from that military and moral failure. But it's good that he seems to have heeded the lessons and led better through this crisis.

That's no guarantee of success, as Biden himself acknowledged. But unlike in Afghanistan, the president pledged that the country would be prepared "no matter what happens.

"We are ready with diplomacy — to be engaged in diplomacy with Russia and our allies and partners to improve stability and security in Europe as a whole. And we are ready to respond decisively to a Russian attack on Ukraine, which is still very much a possibility."

A possibility, yes, but not yet a certainty, in part because of the preparation. The goal must be to push Putin to negotiate legitimate security issues instead of invading Ukraine and starting what Biden rightly called a "war of choice," not a "war of necessity."