Today, Russia has amassed troops to the north, east and south. The United States has disclosed intelligence showing that Russia’s military has a war plan envisioning an invasion with as many as 175,000 troops that Ukraine’s military, despite U.S.-provided equipment and training, would have little ability to stop.
American officials have said it is unclear whether President Vladimir V. Putin of Russia has decided to invade.
Russia has demanded that NATO pledge to refrain from any eastward expansion, that Ukraine cease deployments of NATO weaponry and that Kyiv bend to Russian terms for a settlement in the war in eastern Ukraine.
The buildup places Mr. Zelensky’s government in a crucible of diplomacy and military posturing, which has included U.S. and European military flights near Russia’s borders in the Black Sea and a video call between President Biden and Mr. Putin.
Military analysts have described a range of scenarios for conflict, including a limited use of force by Russia. But a full invasion would become the largest military action in Europe since World War II, harden the continent’s East-West divide and kill an untold number of soldiers on both sides, as well as civilians in Ukraine.
It is hardly a lighthearted moment, and yet comedy was integral to Mr. Zelensky’s political ascent and persona, and his supporters defend its relevance in crisis.
On television, he played a schoolteacher whose tirade against corruption is filmed by his students, winds up online and goes viral, propelling him to the presidency.