Poland announced Tuesday it is "ready" to "immediately" hand over all its MiG-29 fighter jets to a U.S. air base in Germany to boost Ukraine's fight against Russia.

Ukrainian President Volodymyr Zelenskyy has asked the West and NATO to supply Ukraine with fighter jets.

The Polish government said in a statement that will provide its Russian-made MiGs to the Rammstein Air Base "free of charge," placing them "at the disposal" of the U.S. government, and asked the United States to backfill them "with used aircrafts with corresponding operational capabilities."

"The Polish Government also requests other NATO Allies -- owners of MiG-29 jets -- to act in the same vein," the statement added.

A senior U.S. defense official told ABC News: "We have seen the Polish government’s announcement and have nothing to offer at this time."

A spokesperson for the U.S. Department of State told ABC News they are working with the Polish government and consulting with NATO allies on this.

"This is Poland's sovereign decision to make. We have in no way opposed Poland transferring planes to Ukraine. There are a number of challenging practical question," the spokesperson said. "In the meantime, we continue to surge security assistance for Ukraine and deliveries are ongoing."

A senior U.S. diplomat told ABC News that the U.S. was not "pre-consulted" on this news. U.S. Under Secretary of State for Political Affairs Victoria Nuland told the Senate Foreign Relations Committee that she found out about Poland's announcement while driving to Capitol Hill to testify.

"To my knowledge, it wasn't pre-consulted with us that they plan to give these planes to us, but as you know, we have been having consultations with them for a couple of days now about this request from the Ukrainians to receive this aircraft, and, were they to donate them, whether we would be able to help support backfill in their own security need," Nuland said.

-ABC News' Christine Theodorou and Luis Martinez

Editor's note: This post was updated to reflect the correct fighter jet models as MiG-29s, not MiG-19s.

Ukrainian intelligence claimed Tuesday that a Russian general was killed in fighting near the eastern city of Kharkiv. If confirmed, this would be the second general Russia has lost in Ukraine in a week, according to reports from Russian media last week.

Ukraine’s defense intelligence agency identified the general as Vitaly Gerasimov, chief of staff of the 41st Army.

Ukraine’s defense intelligence agency also published audio of an alleged intercepted phone call between two officers from Russia’s FSB intelligence agency discussing Gerasimov’s death.

Russia has not confirmed or denied the death.

The executive director of the open source group Bellingcat, Christo Grozev, said he had confirmed Gerasimov’s death with a Russian source. Grosev said Bellingcat had also identified the FSB officer in the alleged recording.

Last week, the 41st Army’s deputy commander, Major General Andrei Sukhovetsky, was confirmed by Russian media to have been killed.

-ABC News' Patrick Reevell

Ukrainian President Volodymyr Zelenskyy spoke to the U.K.'s parliament Tuesday, asking it to increase the pressure of sanctions and "make our Ukrainian skies safe."

Zelenskyy has been asking NATO and the West to enforce a "no-fly" zone over Ukraine, but the U.S. and its allies have declined the request.

The Ukrainian president was greeted with rousing applause from members of the House, who stood before he spoke.

In his speech, Zelenskyy quoted Shakespeare, saying, "We have to be or not to be. This is a Shakespearean question. Not that I have the answer, but…Yes it is to be."

He also paraphrased the words of Winston Churchill.

"We will not give up. We will continue fighting for our land whatever the costs. We will fight in the fields, in the seas, in the streets. We will fight on the banks of different rivers," Zelenskyy said.

"We do not want to lose what we have," Zelenskyy said.

-ABC News' Joe Simonetti and Matt Gutman

The European Commission on Tuesday released its proposed plan to make the European Union independent from Russian fossil fuels before 2030, starting with gas.

The plan "will seek to diversify gas supplies, speed up the roll-out of renewable gases and replace gas in heating and power generation," according to the European Commission.

This plan could reduce the EU's demand for Russian gas by two-thirds before the end of the year, according to the European Commission.

"We must become independent from Russian oil, coal and gas. We simply cannot rely on a supplier who explicitly threatens us," European Commission President Ursula von der Leyen said in a statement.

Von der Leyen said she would be discussing the Commission's proposal with European leaders in Versailles later this week.

"Putin's war demonstrates the urgency of accelerating our clean energy transition," the European Commission wrote on Twitter.

Just before the invasion of Ukraine, the EU reported wholesale gas prices were around 200% higher than a year ago. The invasion aggravated the energy crisis even further.

The EU said it is reliant on imports of fossil fuels— gas, oil and coal— to meet its needs.

Last year, Russia provided around 45% of the EU's total gas imports, 27% of the EU's total crude oil imports and 46% of the EU's hard coal imports, according to the European Commission.

-ABC News' Christine Theodorou

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