WASHINGTON (NEXSTAR) — Despite phone calls and public and private warnings from the US and its allies, Russian President Vladimir Putin seems unmoved.

“They could launch a military action essentially at any time,” National Security Advisor Jake Sullivan said.

Sullivan said on CBS’ Face the Nation that the Russian military buildup on the border of Ukraine continues, while the U.S. and its allies continue to prepare for the worst.

“We will defend every inch of NATO territory, every inch of article 5 territory, and Russia, we think, fully understands that message,” Sullivan said.

Sunday morning, President Biden spoke with Ukrainian President Volodymyr Zelensky.

The White House says the two leaders agreed “…to pursue diplomacy and deterrence in response to Russia’s military build-up.”

Pentagon Press Secretary John Kirby told Fox News Sunday that the U.S. remains hopeful for a peaceful outcome.

“We still believe that there’s a way to de-escalate the tensions here, find a peaceful way out of this,” Kirby said.

Lawmakers on Capitol Hill are split on whether to punish Russia with economic sanctions now or wait for the Russians to attack Ukraine.

On ABC’s This Week, House Speaker Nancy Pelosi (D-Calif.) defended the President’s decisions to hold off on sanctions until Russia acts.

“There’s very severe consequences to his aggression and that we are united in using them,” Pelosi said.

But Sen. Lindsey Graham (R-S.C.) believes Congress needs to pull the trigger on sanctions now.

“…Pre-invasion with a waiver, post invasion sanctions that would destroy the ruble and cripple the Russian economy,” Graham said.

Lawmakers and administration officials continue to urge Americans in Ukraine to leave that country now.