Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty

Kyiv mayor Vitali Klitschko said explosions occurred in different districts on both banks in the city on Saturday morning and, in one of the districts, fire broke out in a non-residential area.

There were no casualties as a result of the attack that happened at approximately 6 a.m. but 18 residential houses were damaged in the region, according to the governor Oleksiy Kuleba.

The spokesman for the Ukrainian Airborne Forces, Yuri Ignat, told ABC News that Ukrainian authorities think it could have possibly been a ballistic attack by Russia but could not confirm this.

"Most likely, these are missiles that flew along a ballistic trajectory from the north. Ballistics are not available for us to detect and shoot down," Ignat said on Ukrainian television.

-ABC News' Yulia Drozd

Russian military leaders claim their forces took over the salt-mining town of Soledar.

Video showed Russian soldiers evacuating civilians from Soledar and nearby villages to the city of Shakhtarsk as fighting took place on the outskirts on Friday.

Serhiy Cherevaty, the Ukrainian commander of the Eastern Group of Forces, however, confirmed that fighting was going on in the region but contested Russia's claims about the status of the city in a statement to ABC News.

"We have a clear understanding of who controls which streets in the city, but I cannot reveal those details," he told ABC News.

-ABC News' Ellie Kaufman and Patrick Reevell

Pressure is mounting for key NATO allies to send tanks to Ukraine.

After meeting with Ukrainian President Volodymyr Zelenskyy on Wednesday, Polish President Andrzej Duda said his country plans to supply Leopard tanks to Ukraine but only as part of an "international coalition."

"They will be provided within the coalition, because you know that it is necessary to obtain certain official consents. But first we need to build an international coalition and we have decided to form this international coalition," Duda said.

Duda “expressed hope” other NATO countries would provide Ukraine with tanks as well.

The United Kingdom has not made a final decision on whether to send tanks to Ukraine, according to the spokesperson for British Prime Minister Rishi Sunak. The United Kingdom is considering supplying Ukraine with the British Army’s Challenger 2 main battle tank, according to British media reports.

Germany is also facing pressure from Ukraine and other NATO allies to send tanks to Ukraine. So far, they have not committed to sending any tanks to the country and neither has the United States.

Germany and the United States have both agreed to supply Ukraine with armored carriers and the Patriot air defense system.

Russian and Ukrainian officials offered conflicting views Thursday on the battle being waged over the eastern Ukraine city of Soledar.

Both sides described their forces as making progress in the fight for the salt mining town in the Donbas region.

"Our defenders continue to hold their positions on the most difficult frontlines and in the battle for (the) Donbas," said Hanna Maliar, the Ukrainian deputy of defense. "Today, fierce and heavy battles continue in the direction of Bakhmut, in the area of Soledar city."

Despite the "difficult situation," Ukrainian soldiers are desperately battling for control of Soledar, Maliar said.

"The enemy is suffering heavy losses, unsuccessfully trying to break through our defenses and capture Soledar," Maliar said. "Today, the city's approaches are literally littered with the bodies of Putin's destroyed troops. Nevertheless, they move over the bodies of their fallen fighters. Our defenders show maximum resilience and heroism."

But Kremlin spokesperson Dmitry Peskov said Thursday that Russian forces and mercenaries from the Wagner private military company are doing a "truly colossal job" in Soledar.

"These are absolutely selfless, heroic deeds," Peskov told journalists on Thursday.

Peskov said the hostilities in the region will continue.

"There is still a lot of work to be done. No time to stop, no time to rub our hands and so on. The main work is yet to come," Peskov said.

The Russian Defense Ministry said on Wednesday that Russia's airborne units had blocked Soledar from the north and the south and assault teams were fighting within the town limits.

Ukrainian President Volodymyr Zelenskyy said in his daily address on Wednesday that Ukrainian troops are holding onto Soledar.

"The terrorist state and its propagandists are trying to pretend" to have achieved some successes in Soledar, Zelenskyy said. "But the fighting continues."