The Russian military has seized the city of Kreminna in eastern Ukraine and forced Ukrainian troops out of the town, the governor of the Luhansk region said at a briefing Tuesday, per Reuters.

Why it matters: Kreminna appears to be the first city Russian forces have taken since they launched a new offensive in the Donbas region Monday — a development that marked the start of a second phase of the war centered on a battle for territory in eastern Ukraine.

What they're saying: Russian forces entered Kreminna after launching an attack "from all sides" to take control of the city, according to Gov. Serhiy Gaidai.

• "Our defenders had to withdraw. They have entrenched themselves in new positions and continue to fight the Russian army," he added.
• "It is impossible to calculate the number of dead among the civilian population," he added. "We have official statistics — about 200 dead — but in reality there are many more."
• Gaidai did not specify how long it took Russian forces to establish control of the city, or the length of the period in which the death toll was incurred, per Reuters.

The big picture: Heavy shelling was reported Monday alongside nearly the entirety of the 300-mile frontline in eastern Ukraine, including the Kharkiv, Donetsk and Luhansk regions, according to Oleksiy Danilov, the secretary of Ukraine's National Security and Defense Council.

Ukrainian President Volodymyr Zelensky on Sunday stressed the importance of the battle of Donbas, which he said could "influence the course of the whole war."

State of play: A senior U.S. defense official told reporters Tuesday that while they couldn't confirm the specific reports regarding Kreminna, limited offensive operations have been observed southwest of Donetsk and south of Izyum in Ukraine.

• "We think these offensives are preludes to large offensive operations that the Russians still plan to conduct," they added.
• In concurrence with the offensive operations, the Russians are also continuing to conduct "shaping operations" to reinforce troops and equipment, the defense official said.
• Approximately seven U.S. flights carrying weapons are heading to Europe in the next 24 hours, as part of the $800 million aid package President Biden authorized last week, they added.

A European official briefing reporters Tuesday on the outlook in the Donbas said the latest assessment was that Russia would be able to take the remainder of Luhansk and “a bit” of Donetsk — the two provinces that comprise the Donbas region — as well as a very narrow land corridor to Crimea.

• Mariupol will likely fall within days, and there will be fierce fighting for Kherson, the official said, but Ukraine is otherwise well-positioned to limit the advance.
• Russia could take some additional territory north of the Donbas as leverage for negotiations, but will not push further West or attempt to take the port of Odessa, the official assessed.
• Within four to six months, the official predicted that there would be a stalemate in the Donbas, and the potential for more serious negotiations.

Editor's note: This story has been updated throughout.