Putin's nuclear alert part of 'pattern' of 'manufacturing threats': Psaki

White House press secretary Jen Psaki said Sunday that Russian President Vladimir Putin's decision to put his nation's nuclear deterrent forces on a state of heightened alert was part of a "pattern" of "manufacturing threats that don't exist."

"This is really a pattern that we've seen from President Putin through the course of this conflict, which is manufacturing threats that don't exist in order to justify further aggression," Psaki told ABC "This Week" anchor George Stephanopoulos. "And the global community and the American people should look at it through that prism."

Putin announced Sunday he had ordered his military to put Russia's nuclear deterrent forces in a state of heightened readiness in response to what he called "aggressive statements" from NATO countries.

"We've seen him do this time and time again," Psaki said. "At no point has Russia been under threat from NATO, has Russia been under threat from Ukraine. This is all a pattern from President Putin."

The move came as Western nations rolled out waves of financial sanctions on Russia over its invasion of Ukraine that have the potential to cripple Russia's economy. The U.S. and other nations have also stepped up military aid to Ukraine.

Observers have questioned whether Putin is acting rationally, with a former U.S. ambassador to Russia, Michael McFaul, saying this week that he did not think the Russian president was.

"I wish I could share more," Sen. Marco Rubio, R-Fla., tweeted Friday, "but for now I can say it's pretty obvious to many that something is off with Putin."

Pressed by Stephanopoulos on whether the U.S. government believed Putin was mentally unbalanced in some way, Psaki said the Russian leader had made clear his "ambitions beyond" solely justifying the invasion of Ukraine.

"I'm not going to make an assessment of his mental stability," she said, "but I will tell you, certainly, the rhetoric, the actions, the justification that he's making for his actions are certainly deeply concerning to us."

Asked by Stephanopoulos if President Joe Biden was confident his Ukrainian counterpart, Volodymyr Zelenskyy, was safe, Psaki declined to say and instead praised the Ukrainian leader.

"He has been in close touch," Psaki said. "While not getting into his security -- the security of President Zelenskyy -- I'm just going to note, George, as the American people have seen and tuned in to, he is standing up courageously against the invasion of President Putin and Russian leadership, leading his country and continuing to."

In an earlier interview on "This Week," Ukrainian Ambassador to the U.S. Oksana Markarova told Stephanopoulos that Zelenskyy is "is as safe as our country."

"That's the choice he made to stay in Kyiv, to stay in Ukraine and lead the nation in this very difficult moment," she said.

The United States and its Western allies said Saturday they would target Russia’s central bank and bar some of the country’s banks from participating in a system that facilitates international transactions.

But aside from halting a Russian pipeline that had not yet started pumping gas to Europe, the countries have stopped short of launching crippling sanctions against Russia's oil and gas industry, a major sector of its economy.

Sen. Tom Cotton, R-Ark., has called for the Biden administration to sanction the Russian energy sector while lifting restrictions on drilling on U.S. federal lands and reopening the Keystone Pipeline, which Biden revoked the permit for in June. Stephanopoulos pressed Psaki on those proposals.

"The Keystone Pipeline was not processing oil through the system," Psaki said. "That does not solve any problems. That's a misdiagnosis...of what needs to happen," she said. "I would also note that on oil leases, what this actually justifies, in President Biden's view, is the fact that we need to reduce our dependence on foreign oil, on oil in general, and we need to look at other ways of processing -- of having energy in our country and others."

Much of Western Europe, especially Germany, relies on Russian gas, and the United States has stayed away from hitting Russia's oil and gas sector in order to avoid prices spiking in Europe and the U.S.

"We want to take every step to maximize the impact and the consequences on President Putin, while minimizing the impact on the American people and the global community," Psaki said. "And so energy sanctions are certainly on the table. We have not taken those off. But we also want to do that and make sure we're minimizing the impact on the global marketplace and do it in a united way."

ABC News' Patrick Reevell and Tanya Stukalova contributed to this report.