U.S. President Joe Biden and European Commission President Ursula von der Leyen announced Friday a joint task force to "reduce Europe's dependence on Russian fossil fuels and strengthen European energy security," amid Russia's invasion of Ukraine.

Named the "Task Force for energy security," the group will be chaired by one representative from the White House and one representative from the European Commission. They will work to ensure energy security for Ukraine and the European Union ahead of the next two winters by focusing on two main goals -- diversifying liquefied natural gas supplies and reducing demand for natural gas, according to a fact sheet from the White House.

As part of the agreement, the United States will work with international partners to put more liquefied natural gas on the EU market, pledging to make at least 15 billion cubic meters available in 2022, with increases expected going forward.

The White House stressed that the task force would also work with an eye towards clean energy, looking to reduce greenhouse gas intensity of all new liquefied natural gas infrastructure as well as demand for liquefied natural gas by "accelerating market deployment of clean energy measures." Those measures include expediting planning of clean energy projects, like wind and solar power, and using smart thermostats and heat pumps in homes.

-ABC News' Molly Nagle

U.S. President Joe Biden's final meeting in Brussels on Thursday was with the European Council.

"They reviewed their ongoing efforts to impose economic costs on Russia and Belarus, as well as their readiness to adopt additional measures and to stop any attempts to circumvent sanctions," the White House said in a statement.

The leaders said they willl continue "providing humanitarian assistance, including to neighboring countries hosting refugees, and underscored the need for Russia to guarantee humanitarian access to those affected by or fleeing the violence," according to the White House.

They also "discussed EU-U.S. cooperation to reduce dependence on Russian fossil fuels, accelerate the transition to clean energy, as well as the need to respond to evolving food security needs worldwide," the White House said.

-ABC News' Molly Nagle

Andrey Turchak, the secretary general of United Russia, Russian President Vladimir Putin’s ruling party, has suggested Russia will permanently occupy the besieged Ukrainian city of Mariupol as its forces move closer to capturing the city.

Though Russia is responsible for Mariupol's destruction, Turchak said the party has opened a “humanitarian center” in Mariupol and pledged Russia would rebuild houses and businesses destroyed in the fighting.

"Russia will definitely rebuild all of this," Tuchak said, adding, “No one should have any doubts -- Russia is here forever."

-ABC News' Patrick Reevell

Russia's Defense Ministry claimed Thursday that Ukraine violated regulations when placing sea mines in its territorial waters and that appropriate maps were not prepared.

Russia claimed these violations prevent foreign ships from being able "to safely leave the ports of Mykolaiv, Chernomorsk, Ochakiv, Odesa and Yuzhne and set out to open sea," Mikhail Mizintsev, the head of Russia's National Defense Control Center, claimed at a press briefing.

Mizintsev claimed 76 foreign ships from 15 countries remain blocked in Ukrainian ports.

Russia says in order for foreign vessels stuck at Ukrainian ports to depart safely, it has created a humanitarian corridor beginning Friday.

"The corridor will be operating daily between 8 a.m. and 7 p.m. (Moscow time) beginning from March 25, 2022," Mizintsev said. The corridor will be 80 nautical miles long toward the southwest with a navigation strip width of 3 miles.

Russia also said it evacuated 4,453 people from Mariupol without Kyiv's participation on Thursday.

In total, 86,718 people have already been evacuated from the city, Mizintsev claimed.

All Russian troops have left the Ukrainian cities of Kyiv and Chernihiv, withdrawing north toward the borders of Belarus and Russia to consolidate before likely redeploying to the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters Wednesday.

But even with the Russians gone, the territory remains treacherous.

"There are some indications that they left behind mines and things like that, so the Ukrainians are being somewhat careful in some areas north of Kyiv as they begin to clear the ground and clear the territory and re-occupy it," the official said.

While the U.S. hasn't yet seen these troops redeploy elsewhere in Ukraine, it'll likely happen soon, according to the official. Ukrainian forces are preparing for a major fight in Donbas, the official said.

The official also said the Pentagon is "monitoring" an apparent nitric acid explosion in Ukraine's Luhansk region, which Russia blamed on Ukraine.

"We've seen the Russians claim that this was a Ukrainian attack on this. We do not believe that is true," the official said. "We do believe that the Russians are responsible, but exactly what they used when they did it, why they did it, what the damage is, we just don't have that level of detail," the official said.

The official also noted that a small number of Ukrainians currently in the U.S. for "professional military education" were pulled aside for a couple days of training on Switchblade drones, which the U.S. is sending overseas as part of its military aid, according to the official.

"Although it's not a very difficult system to operate, we took advantage of having them in the country to give them some rudimentary training on that," the official said.

-ABC News' Matt Seyler