Ukrainian forces began pushing into Russia's Kursk region on Tuesday night, catching Russia by surprise and creating a state of emergency.
As of Thursday, Ukrainian troops advanced at least 6 miles, took several settlements and captured dozens of Russian prisoners, while surrounding the city of Sudzha.
They may also have taken a gas measuring facility at Sudzha and have threatened a nuclear power plant in the region.
Russian President Vladimir Putin, who called the incursion into Kursk a "major provocation," has already met with top officials about the attacks and is directing his forces to push Ukraine out.
Russian Maj. Gen. Apty Alaudinov, the deputy head of the main military-political directorate, said the situation was "hard" but "not critical" in Kursk.
"In reality the tide can be turned," he said, according to state-run media outlet TASS.
Ukrainian President Volodymyr Zelensky has not commented on the Kursk attacks, though he mentioned Wednesday night that pressuring Russia was vital.
His advisor, Mykhailo Podolyak, made a cryptic suggestion that Kursk was "karma" for Russia.
"The impossible has become possible, and the mythical Russian brutality and boundlessness has turned against Russia itself," he posted on X.
The U.S. is trying to get more information about the attacks, but Pentagon deputy press secretary Sabrina Singh said the incursion into Kursk is "consistent with our policy."
"We have supported Ukraine from the very beginning to defend themselves against attacks that are coming across the border and for the need for crossfires," she told reporters Thursday. "They are taking actions to protect themselves."
Singh also dismissed concerns of Russia escalating the war or increasing tensions with the U.S. over Kursk.
The fighting in Kursk comes as Russian forces are pressuring Ukraine across the 600-mile frontline, primarily in the eastern Donetsk region and the northeastern Kharkiv region neighboring Sumy.
Read the full report at TheHill.com.
