Red Cross renewed its attempts to send a team to Mariupol on Saturday to evacuate civilians, after a team was unable to reach the city on Friday.

"Our team is on the move this morning from Zaporizhzhia to Mariupol. I'm not able to give further information at this stage," a Red Cross spokesperson said to Reuters.

An estimated 160,000 people are trapped in Mariupol.

A team on Friday had to abandon its plan to send 54 buses and many cars to Mariupol after it was unable to get security guarantees for the convoy.

Pope Francis told reporters Saturday that he is considering making a trip to the Ukrainian capital, Kyiv.

Asked by a reporter on the papal plane taking Francis from Rome to Malta if he was considering an invitation made by Ukrainian political and religious authorities, Francis answered: "Yes, it is on the table." He gave no further details.

The pope didn’t mention Russian President Vladimir Putin by name during his remarks, but said "some potentate" had unleashed the threat of nuclear war on the world in an "infantile and destructive aggression" under the guise of "anachronist claims of nationalistic interests."

"We had thought that invasions of other countries, savage street fighting and atomic threats were grim memories of a distant past," Francis added.

-ABC News' Rashid Haddou

Ukrainian President Volodymyr Zeleneksyy claimed Russian forces are leaving behind "a catastrophic situation" and that they are mining the entire territory.

"Occupiers are retreating in the north of our country, slowly but noticeably. Somewhere they are pushed away with fighting, somewhere they are leaving their positions themselves. After their withdrawal, the situation is catastrophic, and there is so much danger," Zelenskyy said.

Zelenskyy then claimed, "First of all, airstrikes might continue. Secondly, they are mining the entire territory, houses, hardware, even the bodies of those killed. There are so many tripwires and other dangers."

He warned that people returning to these territories should be careful as "it's still not possible to return to normal life as it used to be, even at the territories that we are taking back after the fighting. We need wait till our land is de-mined, wait till we are able to assure you that there won't be new shelling."

Zelenskyy claimed Ukrainians have been able to evacuate 6,266 people, including 3,071 residents of Mariupol. He also said they are discussing the evacuation of the injured and killed military personnel and civilians, with Turkey acting as an intermediary.

Zelenskyy said Russian troops are preparing for new "powerful strikes" in the east and warned that Russia is trying to conscript people in Crimea.

Zelenskyy, speaking in Russian, addressed the Russian people, asking them to, "Warn every conscript and their parents that we don't need more killed people here. Take care of your children so that they don't turn into evil. Don't let them go to the army. Do whatever you can to let them live at home, at their home."

-ABC News' Rashid Haddou

A U.S. intercontinental ballistic missile test that was initially postponed in early March to avoid "misinterpretation" by Russia was recently canceled, the Department of the Air Force said Friday.

Defense Secretary Lloyd Austin originally delayed the routine test flight of an LGM-30G Minuteman III missile after Russia put its nuclear deterrent forces on a state of heightened alert.

"The launch had been previously delayed due to an overabundance of caution to avoid misinterpretation or miscommunication during the ongoing Russian invasion of Ukraine and was cancelled for the same reason," the Air Force said in a statement. "Our next planned test flight is later this year. The Department is confident in the readiness of the strategic forces of the United States."

-ABC News' Matt Seyler

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