Russia did not directly threaten to invade Ukraine, but complained about alleged provocations from the Ukrainian side of their common border. Mr Putin has supported pro-Russian separatist rebels in the east of the former Soviet republic since 2014, when a popular revolution toppled the Putin-backed president of Ukraine. Shortly thereafter, Russia annexed the Crimean peninsula of Ukraine.
In a sign of heightened tensions, the chairman of the Joint Chiefs of Staff, General Mark A. Milli, spoke on the phone with his Russian counterpart, General Valery Gerasimov, on Tuesday. The Pentagon said in a statement that the appeal was intended to “reduce risk and resolve conflicts quickly.”
Ukrainian President Volodymyr Zelensky said the United States is providing Kiev with information and data on the Russian troop build-up. Western officials have confirmed that NATO allies are stepping up intelligence exchanges with Ukraine in the hope that a better understanding of the growing threat will help Kiev better prepare and better contain Moscow.
Most analysts believe that even in the worst case scenario, Kiev should not expect the US military to come to its aid.
“The Russians know very well, as they have been invading Ukraine for seven years now, that we are not going to send 82nd Airborne Division,” said Samuel Charap, a former State Department official now at RAND. “And I think they’ve probably appreciated everything other than that, in the sense that they’re willing to pay the price.”
“That’s what makes it difficult,” he added. “There is no easy way out of this.”
US officials have said they do not believe that Mr. Putin has yet decided whether to take military action against Ukraine. While the threat is being taken seriously, officials say, the United States and its allies have time to try to prepare Kiev and convince Moscow that such a move would be a terrible mistake.
Whatever Mr. Putin may think, his troop build-up is likely to test the readiness of the United States, NATO and Europe to act.