The United States has said it believes Russia is reinforcing and repositioning its troops in Ukraine’s eastern region of Donbas, where Ukrainian officials say Russian forces are preparing to launch a fresh offensive.
In a news conference on Monday, Pentagon Press Secretary John Kirby said a convoy of Russian vehicles had been observed heading towards the town of Izyum, about 180km (112 miles) north of the city of Donetsk.
But “it’s not clear to us how many vehicles are in this convoy and what exactly they’re bringing”, Kirby told reporters, adding that it appeared to be a mix of personnel-carrying vehicles as well as armoured vehicles “and maybe some artillery”.
“They’re repositioning, they’re refocusing on the Donbas,” he said.
A senior US defence official said earlier on Monday that the US does not believe a “new offensive” in the Donbas region has begun yet, but that Russian forces “are working to reinforce their capabilities and to add to it”.
The comments from officials in Washington come as Ukraine has said it is preparing for a Russian offensive in the eastern part of the country, after Moscow withdrew from areas around the capital, Kyiv.
Russia now says its main objective is the east, and it is demanding Ukraine cede control of swathes of territory there to separatist fighters.
Ukrainian President Volodymyr Zelenskyy told Al Jazeera that Russia could launch another offensive against Kyiv should it gain control of the eastern breakaway region.
“If our forces in Donbas won’t be able to hold their positions, then the risk of a repeated offensive against Kyiv and Kyiv Oblast [province] is almost probable,” Zelenskyy said in an exclusive interview.
Al Jazeera’s Resul Serdar, reporting from Kyiv, said most Russian forces have been redirected from the Kyiv region towards Donbas.
“All the indications show that they are making preparations to start to initiate a new, huge assault on this region,” Serdar said. “As the Russian forces are amassing there, concerns are growing in cities like Mariupol, which is besieged from all directions.”
Zelenskyy said on Monday that tens of thousands of people had been killed in Mariupol since Russian forces first lay siege to the Ukrainian port city weeks ago. Al Jazeera could not independently verify that figure.
In his comments to reporters, Kirby at the Pentagon said he also could not confirm that estimate as the city is “still being fought over”.
“But if you just look at the imagery, and you see how much the Russians have pounded Mariupol from the air, it’s inconceivable to imagine that there aren’t going to be civilian casualties, and that it could be a significant number,” he said.
Kirby also underscored that the Ukrainian military has been fighting Moscow-backed separatists in the Donbas region since 2014.
“The Ukrainians have been for eight years – and still are – fighting over that,” he said. “And they show no signs of being willing to give that territory up.”