Ukraine's air force claimed Friday that Russia carried out an alleged false flag airstrike in a Belarusian village near the border with Ukraine.

In a post on Facebook, Ukraine's air force claimed Russian jets took off from a base in Belarus and entered Ukraine's airspace, then a fire started in the village of Kopani.

Ukraine's Defense Minister Oleksy Reznikov earlier claimed in a Facebook post that Russian forces would launch a strike against Kopani to "pull the armed forces of the Republic of Belarus into the war with Ukraine."

-ABC News' Patrick Reevell

Ukraine Defense Minister Oleksy Reznikov on Friday accused Russia of preparing to carry out airstrikes against Belarusian villages close to the border with Ukraine in order to create a pretext for Belarus entering the war more directly.

Until now, Belarus has largely only acted as a base for Russia’s invasion forces and for missile and air strikes to be launched from its territory.

Ukraine claims it has information that Russia is planning to launch a series of false flag airstrikes against Belarusian villages to try to change that and create a push for war within Belarus, Reznikov said in a post online.

"I appeal to the Belarusian people. Friends. According to information in which we are completely sure and which we have confirmed, at the present moment the command of the Russian occupation troops is preparing a series of bloody provocations," he said.

Reznikov added, "According to their criminal conspiracy, Russian aviation is preparing to launch a strike on a range of population centers on the territory of Belarus, located close to the Ukrainian-Belarusian border."

He named the village of Kopani in the Brest region.

He denied Ukraine would ever launch strikes and said, "the goal of the provocation is to push the acting leadership of Belarus towards war against Ukraine. Moscow is trying to bind you with blood."

-ABC News' Patrick Reevell

The U.S. Department of Commerce announced Friday that it will restrict the export of U.S. luxury goods to Russia and Belarus, as well as "certain Russian and Belarusian oligarchs and malign actors located worldwide," as a result of their actions in Ukraine.

The Department of Commerce said it will impose restrictions on the export, reexport and transfer of luxury items including certain spirits, tobacco products, clothing items, jewelry, vehicles and antique goods.

"Putin’s war of choice in Ukraine continues to take a devastating toll on innocent civilians in Ukraine, fueling one of the worst humanitarian crises Europe has seen in decades," Secretary of Commerce Gina Raimondo said in a statement.

Raimondo added, "Putin and the oligarchs who fund him have gotten rich off of Putin’s rampant corruption and the exploitation of the Russian people. We will not allow Putin and his cronies to continue living in opulence while causing tremendous suffering throughout Eastern Europe. Today’s action takes away another source of comfort and reminds them that Russia is increasingly isolated."

-ABC News' Luke Barr

The World Health Organization said Friday that it is urging Ukraine to now destroy its pathogen samples because Russia's war in the country risks an "accidental spill," according to WHO spokesperson Tarik Jašarević.

"This is part of us providing a public health advice to every country to try to ensure there is a minimized risk of any harm to population because of any possible accidental leak of pathogens," Jašarević said Friday from Lviv.

-ABC News' Conor Finnegan

The Russian forces charging toward Kyiv haven't made progress in the last day as they face Ukrainian resistance and low food and gas supply, a senior U.S. defense official told reporters Tuesday.

However, it could be a deliberate pause, the official said. "Part of the stall could be ... as a result of their own self-determined sort of pause in operations -- that they are possibly regrouping, rethinking, reevaluating," the official said.

The U.S. believes Russian forces "have committed now more than 80% of what was their pre-staged combat power," the official added.

The official said some Russian soldiers weren't told they were going into combat. The official said "not all of them were apparently fully trained and prepared."

The strong Ukrainian resistance has also hurt morale, according to the official.

Russia has now launched more than 400 missiles on Ukraine, the official said. The U.S. believes Russia has launchers that could be used for thermobaric weapons, but cannot confirm their use, the official said.

Russian forces are making the most progress in the south. Russians are attacking Kherson in south Ukraine, which "appears very much to be contested city at this point," the official said.

Russians are also approaching Mariupol in southeastern Ukraine, and while they haven't yet entered the city, "they are close enough now that they could attack Mariupol with long range fires," the official said.

Two towns on the path to Mariupol are believed to be occupied by the Russians, according to the official.

The U.S. believes the Russians hope to move north out of Mariupol up to the heavily-contested city of Kharkiv. The official said they believe Russian forces are trying to encircle Kharkiv.

The U.S. official noted that they've seen "certain risk-averse behavior by the Russian military" over the last week.

"Take the amphibious assault, for instance. They put those troops ashore a good 70 kilometers away from Mariupol because they knew Mariupol was going to be defended and they could put them ashore in an uncontested environment. And they still haven't reached Mariupol," the official said.

"They are not necessarily willing to take high risks with their own aircraft and their own pilots," the official said.

"And of course we're seeing that on the ground -- the fairly slow and steady progress that they have made, and you guys are seeing it for yourselves on the ground where ... units are surrendering, sometimes without a fight."

-ABC News' Matt Seyler