Russia-Ukraine updates: US to ban Russian carriers from its airspace

Russian-controlled separatists have formally appealed to Russian President Vladimir Putin for military assistance "in repulsing Ukrainian aggression", according to the Kremlin's spokesman.

In a letter, the separatist leaders invoked the mutual defense pact Russia signed with them after recognizing them.

Ukrainian officials, meanwhile, have maintained that Russia is the aggressor on the ground.

Asked by ABC News reporter Ike Ejiochi whether the formal request from the separatists to Putin was a signal that the U.S. expects a broader invasion is about to begin, White House press secretary Jen Psaki said it was "an example" of "a range of false flag operations" the U.S. had expected.

"As we've said from the beginning, there are going to be a range of false flag operations that we have expected to and laid out the playbook to see," Psaki said during her on-cam briefing this afternoon. "This is an example of it."

"That is suggesting that they feel under threat by whom? The Ukrainians that the Russians are threatening to attack," she continued. "So we'll continue to call out what we see as false flag operations or efforts to spread disinformation about what the actual status is on the ground."

-ABC News' Patrick Reevell and Ben Gittleson

Pentagon press secretary John Kirby, at an afternoon press briefing on Wednesday, said Russian forces are now prepared for an invasion of Ukraine.

"What we see is that Russian forces continue to assemble closer to the border and put themselves in an advanced stage of readiness to act to conduct military action in Ukraine," Kirby said. "We believe that they are ready."

He said that the U.S. does not know when or how an invasion might begin but repeated President Joe Biden's message that if a large-scale invasion happens, it will be a "war of choice" for Putin.

"There will be suffering, there will be sacrifice, and all of that must and should be laid at his feet because he's doing this by choice," Kirby said. 

"I would hope that he understands that some of those lives at risk will be his soldiers' lives and he's going to have to answer to Russian moms and dads about their soldiers that aren't making it back home alive or making it back with injuries. He's going to have to answer for that," Kirby added later.

Kirby went farther than a senior defense official who spoke to reporters earlier Wednesday, saying the U.S. "certainly" believes Russia is sending additional troops into the separatist-controlled areas of Donbas. 

"We can't confirm with any great specificity, the numbers and what the formations are, what the capabilities are, but we certainly that that's happening," he said.

-ABC News' Matt Seyler

State Department spokesperson Ned Price told reporters at Wednesday's briefing that "Russia's invasion of Ukraine is beginning."

Price outlined the sanctions placed on Russia, including President Joe Biden's recent sanctioning of Nord Stream 2 AG, the company in charge of the natural gas pipeline from Russia to Germany. 

"By acting together with the Germans, how we did when we did and the way in which we did, we have ensured that this is an $11 billion prize investment that is now a hunk of steel, sitting at the bottom of the sea," Price said. 

Echoing remarks from Secretary of State Antony Blinken on Tuesday, Price said the U.S. will no longer engage in the "pretense of diplomacy" with Russia, adding, "This is and has been, in some ways, diplomatic Kabuki theater on the part of the Russians.

"The goal now is to "avert the worst-case scenario" in Ukraine, he said, which may include "an attack on major urban centers, including Kyiv" and "horrific human rights abuses, atrocities, potential war crimes.”

"These are all things that even as the invasion is beginning, we are going to do everything we reasonably can to prevent from happening," Price said.

When asked about former President Donald Trump and former Secretary of State Mike Pompeo praising Russian President Vladimir Putin this week, Price replied, "I have no response. In fact, I have no words."

House Speaker Nancy Pelosi referred to Russian President Vladimir Putin as a "tyrant" on Wednesday and defended President Joe Biden's handling of the crisis in Ukraine.

"This is the same tyrant who attacked our democracy in 2016," Pelosi said during her weekly press briefing. "This is the same tyrant who is opposed to democracy and wants to minimize, trivialize it, to downgrade it in the eyes of the Russian people." 

While Biden has faced political attacks from some Republicans who argue U.S. sanctions do not go far enough, Pelosi called the president's actions "appropriate." 

"This is a unified effort by our allies in the NATO alliance. And what was proposed was what was agreed to in terms of timing," she said.

ABC News' senior congressional correspondent Rachel Scott asked Pelosi and other lawmakers if they believe the sanctions announced by the administration Tuesday were enough to deter Putin.

"I think the sanctions are going to just continue to increase and we'll have an ultimately crippling impact on many sectors of the Russian economy," Rep. Adam Schiff, D-Calif., responded.

Pelosi added that Russia hasn't seen the "depth" of the sanctions take hold yet. 

"Putin is probably the richest man in the world," Pelosi said. "Follow the money. That's what's the sanctions are about."

-ABC News' Mariam Khan