The eastern Ukrainian village of Stanytsia Luhanska village was shelled with heavy weapons from the “occupied Donbas” area, according to Foreign Minister Dmytro Kuleba in Twitter post on Thursday.

“Civilian infrastructure damaged. We call on all partners to swiftly condemn this severe violation of Minsk agreements by Russia amid an already tense security situation,” he wrote on Twitter.

Since 2014, the Donbas area has been occupied by what Ukrainian and Western forces say are pro-Russian separatists. A photograph posted online allegedly showed damage to a kindergarten in  Stanytsia Luhanska.

Ukraine’s President Volodymyr Zelenskiy alleged that pro-Russian forces had shelled a kindergarten, in what he called a “big provocation.” For its part, the Kremlin said Moscow was “seriously concerned” about reports of an escalation after the separatists accused government forces of opening fire on their territory four times in the past 24 hours.

The self-proclaimed Luhansk People’s Republic, one of two rebel regions, said Ukrainian forces had used mortars, grenade launchers, and a machine gun in four separate incidents on Thursday.

“Armed forces of Ukraine have crudely violated the ceasefire regime, using heavy weapons, which, according to the Minsk agreements, should be withdrawn,” the separatists said in a statement.

Responding to the reports of shelling, Pentagon chief Lloyd Austin, who is in Brussels for a NATO conference, said the United States is looking into claims that the kindergarten was shelled. The incident, he said, is “certainly troubling” and asserted “we have said for some time that the Russians might do something like this in order to justify a military conflict so we will be watching this very closely.”

For weeks now, White House officials have repeatedly warned that Russia—which they say has amassed well over 100,000 troops near Ukraine’s borders—would invade its neighbor. Moscow has categorically denied those allegations and has said it’s the United States and NATO that are trying to spread propaganda to cause the pretext for a war in Eastern Europe.

NATO Secretary-General Jens Stoltenberg on Thursday claimed Russia has the resources now to conduct “a full-fledged invasion of Ukraine” with little-to-no warning. In a dispute of Russian and Belarussian statements that their troops are conducting military drills in the area, Stoltenberg said it is “not a normal exercise.”

“And that is what makes this situation so dangerous,” Stoltenberg told reporters. “So we know about their capabilities but of course we don’t know with certainty about their intentions, so it remains to be seen what they will do.”

This week, there were reports claiming that Russia would attack on Feb. 16, which never materialized. Responding to allegations Russia now might launch an attack on Feb. 20, Chief Kremlin spokesman Dmitry Peskov described such statements as false.

“It looks like another fake has been coined. I hope that at least you and me will not trust such falsehoods,” he told the TASS news agency. “There have been many dates, and far more specific ones … all turned out to be falsehoods, irresponsible fakes, but none of their authors eventually acknowledged they were wrong,” Peskov said.