WARSAW, Poland — Catholic clergy have warned of a decisive stage in the Ukraine war, as Russian forces prepare a new offensive against the country’s eastern Donbas region.

“Everything will be decided by the fight in the Donbas — if they’re victorious there, they’ll go further and try to capture the whole of Ukraine,” said Msgr. Gregory Semenkov, chancellor of Ukraine’s Latin-rite diocese based in Kharkiv.

“What’s most important are the morale and spirit of our own soldiers, and whether they’re capable and willing to go on defending the country. Will weapons be enough for us, in the face of such a mightier power?”

Semenkov spoke to Catholic News Service April 12, as Russian forces began gathering for the new campaign, after being pushed back with heavy losses from areas around Kyiv. Western analysts said the new offensive would be an attempt to link Russian territory to Ukraine’s occupied southern coast.

Semenkov said many Catholics had died in the besieged port of Mariupol, adding that some priests and nuns had been forced to withdraw from other towns under Russian attack.

“My own city of Kharkiv remains under constant fire, as they try to prevent our army moving to defend Donetsk and Luhansk,” Semenkov said.

“The Russians are preparing to fling all their available forces into heavy combat in the east, where the shelling is already intensifying. In this situation, we need the prayers and support of Western Catholics.”

The U.N. Human Rights Council reported April 12 it had documented more than 1,800 civilian deaths and nearly 2,500 injuries since Russia’s invasion Feb. 24, but said actual figures would be “considerably higher.”

Meanwhile, the U.S. and British governments said April 12 they were investigating reports of Russian chemical attacks on last-ditch defenders in Mariupol.

A priest in embattled Kramatorsk said it, too, had remained “under constant fire” since at least 50 civilians were killed in an April 8 Russian missile attack on the town’s main rail station.

“Though we have no news as to whether Catholics were caught up in the blast, many are now on the road to other towns in central and western Ukraine,” Father Victor Vonsovich of Kramatorsk’s Holy Spirit Parish told CNS April 12.

“The situation is completely uncertain — it can be quiet for half an hour, and then they can start shelling and bombing again, with no one knowing which districts might be hit.”

“My own area remains under Ukrainian control, but anyone entering or leaving can be hit by a shell or Grad rocket and end up dead,” the priest told CNS.

“I’m now the only priest left in this church deanery, and I’ve made no preparations to leave, despite fears the atrocities which happened in towns near Kyiv could soon happen here.”