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

Russian-backed separatists in eastern Ukraine claimed a significant deterioration along the front line with Ukrainian government forces on Thursday, accusing Ukraine of launching "large-scale" shelling of civilian areas in the breakaway regions.

Fears that Russia might use such claims as a pretext to launch an invasion remain high, with Thursday's allegations out of the ordinary. The Ukrainian government has denied any intention to launch an offensive on the separatist-held areas.

Local authorities in the self-declared Donetsk and Luhansk people's republics, in an area of southeastern Ukraine known as the Donbas, accused Ukrainian government forces of shelling nine population centers, using large caliber mortars that are banned by a ceasefire.

The separatists' military forces issued "emergency statements" Thursday alleging that "the situation along the line of contact has substantially worsened" in recent days. Rodion Leshchenko, a political advisor to the self-proclaimed Luhansk People’s Republic, accused Ukraine of launching a "massive provocation," allegedly firing 200 times into Donbas.

Kremlin spokesman Dmitry Peskov commented on the claims Thursday, telling reporters "it's absolutely clear that the situation is escalating."

"We hear over the course of the last several days reports that, in short, Russia is maintaining huge offensive potential on the border. But we're talking about our own territory," Peskov said. "But no one, not one Western representative is talking about the huge offensive potential of the Ukrainian Armed Forces on the contact line."

For the past few weeks, Russian propaganda and the separatists in Donbas have been laying the groundwork to accuse Ukraine of launching an offensive, claiming that the Ukrainian government has been massing its forces and also alleging to have found evidence of atrocities. Russian President Vladimir Putin said earlier this week that he believes "genocide" has occurred in Ukraine.

-ABC News' Patrick Reevell

The United Nations Security Council will meet Thursday to discuss the Minsk agreements -- the series of agreements between Ukraine and Russia that were meant to end the Russian-led separatist conflict in eastern Ukraine.

Vassily Nebenzia, Russia's envoy to the U.N., announced the session earlier this month when Moscow took control of the rotating Security Council presidency for the month of February.

The meeting takes on greater urgency this week, especially after the lower house of Russia’s parliament, known as the Duma, voted to ask Russian President Vladimir Putin to recognize those separatists as independent republics.

Ukraine has urged the Security Council to consider the Duma motion during the meeting, Ukrainian Foreign Minister Dmytro Kuleba said on Twitter Wednesday. 

-ABC News' Conor Finnegan

Vice President Kamala Harris this week will make one of her most significant foreign policy trips since taking office, heading to Germany to lead the U.S. delegation at the Munich Security Conference -- where she will meet with Ukrainian President Volodymyr Zelenskyy.

"We are in a very decisive moment," a senior administration official told reporters as Harris prepared to lead the U.S. delegation, calling it a "resounding signal that engagement with our allies and partners is an absolutely critical part of our overall diplomacy in our approach to this situation."

During the Wednesday night call, senior administration officials said the tensions with Russia will be a major focus of the vice president's time abroad, with her schedule featuring a "series of high-stakes, high-level diplomatic talks."

Harris' most notable meeting will be with the Ukrainian president on Saturday.

"That'll be a real opportunity to underscore our commitment to Ukraine sovereignty and territorial integrity and to further coordinate the diplomatic efforts that have been underway to provide economic, and defensive security in Ukraine," an official said.

Harris is also expected to meet with NATO Secretary General Jens Stoltenberg, German Chancellor Olaf Scholz, and the leaders of Latvia, Lithuania and Estonia.

She will deliver keynote remarks at the conference, where she is expected to address the situation on Ukraine's borders -- touching on diplomatic, military and economic coordination of allies. 

"The vice president will underscore how that unity is a source of strength that will allow us to respond quickly and severely to any further Russian aggression," an official said.

-ABC News' Molly Nagle

Russia has increased its presence along the Ukrainian border by as many as 7,000 troops in the last few days, with some arriving Wednesday, a senior White House official told ABC News.

The assessment comes a day after the Russian government said it has started to withdraw some troops from near Ukraine's borders.

The official didn't comment on the total number of Russian forces currently along the border. 

President Joe Biden said Tuesday that Russia has "more than 150,000 troops encircling Ukraine and Belarus and along Ukraine's border." It's unclear if that number includes any of the new troops cited by the official.

Private satellite imaging company Maxar on Wednesday released over two dozen new images from the last 48 hours that continue to show Russia's heightened military activity in Belarus, Crimea and western Russia.

They include images that show a new 20-strong attack helicopter unit deployed in Belarus, a field hospital in Belarus and a pontoon bridge that has appeared across a river in Belarus, four miles from Ukraine’s border.

At least three of the images indicate some troops have departed or are preparing to depart, according to Maxar, though it's unclear where the troops are going.

-ABC News' Mary Bruce and Patrick Reevell