By Sandra Rose  | 

AFP via Getty Images

The world is reacting to Russia invading Ukraine as Russian President Vladimir Putin orders his troops over the border into eastern Ukraine.

A senior Biden administration official told reporters Monday, "In the last hour, we've seen Russia order troops to deploy into the [Donetsk and Luhansk regions] for so-called peacekeeping functions."

TASS via Getty Images

The US ambassador to the United Nations says Putin's claims about "peacekeeping" forces on the ground are "nonsense".

Putin is pictured during a meeting at Moscow's Kremlin on Feb. 22.

US Pres. Joe Biden signed an executive order imposing sanctions on Russia if the invasion into Ukraine continued.

"To be clear: these measures are separate from and would be in addition to the swift and severe economic measures we have been preparing in coordination with Allies and partners should Russia further invade Ukraine," White House press secretary Jen Psaki said on Monday.

She said Biden placed a secure phone call to Ukrainian President Volodymyr Zelensky to "reaffirm the commitment of the United States to Ukraine's sovereignty and territorial integrity" and "strongly condemned" Putin's recognition of Ukraine's rebel republics of Luhansk and Donetsk as independent.

Psaki said Biden had spoken with Zelensky for about 35 minutes — after Putin recognized the two regions as independent regions that he can lay claim to.

The two regions — collectively known as the Donbas — are in eastern Ukraine, near the border with Russia.

The Biden administration previously warned Putin that formally recognizing Luhansk and Donetsk as "independent" would be met with a "swift and firm response" from the U.S. and its allies.

The Biden administration official "made clear that [Putin] views Ukraine historically as part of Russia... This was a speech to the Russian people to justify war," he said.