Biden: U.S., allies will act 'swiftly, decisively' to any Russian aggression against Ukraine

WASHINGTON — President Joe Biden in a nearly hourlong phone call with Ukrainian President Volodymyr Zelenskyy promised that the United States and European allies will act "decisively" to prevent Russia from launching an attack on the fledgling democracy.

"President Biden made clear that the United States would respond swiftly and decisively, together with its Allies and partners, to any further Russian aggression against Ukraine," the White House wrote in a statement issued after the call. "The two leaders agreed on the importance of continuing to pursue diplomacy and deterrence in response to Russia’s military build-up on Ukraine’s borders."

The call came a day after Biden spoke by phone with Russian President Vladmir Putin with neither side reporting any breakthrough in the current diplomatic standoff.

The United States updated its estimate of the Russian forces now staged near Ukraine's borders to more than 130,000, up from the 100,000 the United States has cited publicly in previous weeks. A U.S. official gave the estimate to The Associated Press, speaking on condition of anonymity.

A range of military equipment has also been deployed along Russia’s border with Ukraine, and Russia has increased its troop presence in neighboring Belarus in preparation for an attack, U.S. and NATO officials said.

Last week, Russia moved six amphibious assault ships into the Black Sea, augmenting its capability to land on the coast, the AP reported.

White House national security adviser Jake Sullivan, appearing on a pair of Sunday morning political talk shows, urged U.S. citizens living in Ukraine to "avail themselves" of all commercial travel options out of the eastern European nation, adding that the United States would not send troops to rescue those who stayed.

His warning came as a number of international airline carriers have suspended flights to Ukraine in response to the growing tensions in the region. "If there is a military invasion of Ukraine by Russia, it's likely to begin with a significant barrage of missiles and bomb attacks," Sullivan said on CNN’s "State of the Union." "Those are never as precise as any army would like them to be, and we don't even know how precise the Russian army would like them to be.

"So, innocent civilians could be killed regardless of their nationality. It would then be followed by an onslaught of a ground force moving across the Ukrainian frontier, again, where innocent civilians could get caught in the crossfire or get trapped in places that they could not move from."

Putin has been pressing the United States and other western European leaders to block Ukraine from joining the NATO security alliance, but the heads of state have pushed back, arguing that as a sovereign democratic country, Ukraine has the right to seek entry into the decades-old group.

Pentagon press secretary John Kirby, appearing on "Fox News Sunday," said there is a "shrinking" window of time to reach a compromise, but the Biden administration continues to believe there is a "diplomatic path forward."

"Certainly, we recognize the time component here seems to be shrinking, and that gives us all cause for concern," Kirby said, before adding that the United States still believes "that there's a way to de-escalate the tensions here, find a peaceful way out of this so that a war in Ukraine can be averted."