In the meantime, Biden's two-day visit to Poland and Latvia was all about providing reassurances that the U.S. commitment to defend its NATO allies is "ironclad."
"Have no doubt: The United States will honor its commitment," Biden said. "We always do."
The vice president said new NATO training and exercises will take place in Poland. At Warsaw's request, the U.S. last week sent some 300 air troops and a dozen F-16 fighters to Poland for joint training in a show of military support for a key ally. Biden also said the U.S. is considering rotating American forces to the Baltic region to conduct ground and naval exercises, plus engage in training missions.
As for Russia's actions in Ukraine, Biden dismissed them as "nothing more than a land grab."
"It's a simple fact that Russia's political and economic isolation will only increase if it continues down this dark path," Biden said, adding that virtually the entire world rejects the referendum in Crimea on Sunday that cleared the way for Russia to absorb it.
The vice president met with leaders of Poland and Estonia in Warsaw on Tuesday and was scheduled to see the leaders of Lithuania and Latvia on Wednesday in the Lithuanian capital of Vilnius. All four nations share borders with Russia and are members of the NATO alliance.
Former Soviet states are among those most concerned that Moscow could be resuming its traditional imperial ambitions. But Ukraine is at greater risk because it lacks membership in NATO and the promise of collective defensive measures that comes with it.
Putin, who is anxious to keep Ukraine from tacking toward the West, offered a reassurance that he had no intention of invading other regions of Ukraine that seemed to carry an undercurrent of a warning with it.