Video has emerged purportedly showing trenches and tank tracks in Ukraine's radioactive Red Forest.

The Ukrainian Ministry of Defense released the footage on Wednesday, claiming it as evidence that Russia ordered its soldiers to dig fortifications in the Red Forest near the shuttered Chernobyl nuclear power plant while occupying the area.

"Complete neglect of human life, even of one's own subordinates, is what a killer-state looks like," the ministry said in a post on Twitter alongside the video.

The Red Forest is the most radioactively contaminated part of the exclusion zone surrounding Chernobyl, the site of the world's worst nuclear disaster in 1986.

Russia claimed Thursday that its forces destroyed more fuel depots in Ukraine overnight.

The Russian Ministry of Defense said in a statement that "high-precision air- and sea-based missiles" struck four fuel storage facilities "during the night" near the Ukrainian cities of Mykolaiv, Zaporizhia, Kharkiv and Chuhuiv, from which the ministry claimed "Ukrainian forces were supplied with fuel" near Kharkiv, Mykolaiv and Donbas.

Russia's military remains focused on progressing its offensive operations in eastern Ukraine, the U.K. Ministry of Defense said Thursday in an intelligence update.

According to the ministry, Russian forces continue to conduct artillery and air strikes along the line of control in eastern Ukraine's Donbas region. Russian strikes against Ukrainian infrastructure targets are likely intended to degrade the ability of Ukraine's military to resupply as well as to increase pressure on the Ukrainian government, the ministry said.

"Despite refocusing forces and logistics capabilities to support operations in the Donbas," the ministry added, "Russian forces are likely to continue facing morale issues and shortages of supplies and personnel."

The United States Senate unanimously approved major legislation late Wednesday to resurrect a World War II-era policy that gives President Joe Biden the authority to expedite the delivery of weapons and other supplies to Ukraine amid Russia's invasion.

The so-called Lend-Lease program was created during the Second World War and allowed the U.S. to swiftly resupply allies without bureaucratic barriers in the fight against Nazi Germany. The bill that passed in the Senate on Wednesday night would enable the U.S. to stay physically out of the ongoing war between Russia and Ukraine while providing allies with weapons and military equipment.

In a brief, late-night speech on the Senate floor in Washington, D.C., Senate Majority Leader Chuck Schumer (D-N.Y.) accused Russian President Vladimir Putin and his military forces of carrying out "genocide" in Ukraine, calling the alleged atrocities "pure evil."

"When we murder wantonly innocent civilians because of who they are, whether it be their religion, their race, or their nationality, that is genocide," Schumer said, "and Mr. Putin is guilty of it."

The Ukraine Democracy Defense Lend-Lease Act of 2022, as it's called, would be specific to Ukraine and Eastern European nations to help remove obstacles to lending arms. The legislation would not create a new program, but would streamline the president's current authority to lend the defense articles needed by Ukraine and Eastern European countries and expedite the delivery of defense articles to Ukraine. It would remain in effect through fiscal year 2023, according to a press release from the office of U.S. Senator Jeanne Shaheen (D-NH), chair of the Senate Foreign Relations Subcommittee on Europe and Regional Security Cooperation and a senior member of the Senate Armed Services Committee.

Shaheen introduced the bill with Sens. John Cornyn (R-Texas), Ben Cardin (D-Md.) and Roger Wicker (R-Miss.) in January. It will now be considered by the U.S. House of Representatives.

-ABC News' Trish Turner

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