WASHINGTON (NewsNation Now) — President Joe Biden warned Russian President Vladimir Putin during a high-stakes call on Saturday that if Russia invades Ukraine, the United States, along with its allies, will impose “swift and severe costs” on Russia.

“President Biden was clear with President Putin that while the United States remains prepared to engage in diplomacy, in full coordination with our Allies and partners, we are equally prepared for other scenarios,” the White House said in a news release.

Biden told Putin a further Russian invasion of Ukraine would produce widespread human suffering and diminish Russia’s standing, the news release said.

This call came amid warnings White House officials and others have made that Russia could invade Ukraine any day now, as the country continues to build up firepower near there.

The White House said the call, which Biden conducted from Camp David, lasted a little more than an hour. It started at 11:04 a.m. ET and ended at 12:06 p.m.

According to a senior administration official, there was no fundamental change in the dynamic between the two countries, but both presidents agreed that they will keep in touch in the days ahead.

On Saturday, the U.S. told most of its employees to evacuate the Embassy in Kyiv, and that it is suspending consular services there starting Saturday. The White House had previously said that any American citizens in Ukraine should leave immediately.

U.S. National Security Adviser Jake Sullivan said during a press briefing Friday that the United States will not be sending its own troops to Ukraine to help American citizens evacuate.

“The president will not be putting the lives of our men and women in uniform at risk by sending them into a war zone to rescue people who could have left now but chose not to,” Sullivan said.

Speaking to Russian Foreign Minister Sergey Lavrov Saturday, U.S. Secretary of State Antony Blinken told him that if Moscow pursues the “path of aggression” by invading Ukraine, it will result “in a resolute, massive and united Transatlantic response.”

Also on Saturday, Defense Secretary Lloyd Austin ordered the temporary repositioning of the 160 Florida National Guard members who have been deployed to Ukraine since late November.

Those troops had been advising and mentoring Ukrainian forces as part of Joint Multinational Training Group-Ukraine, Pentagon Press Secretary John F. Kirby said in a statement.