Russia has banded together up to 20,000 lightly equipped mercenaries to fight in the “battle for Donbas,” according to a report on Tuesday.

The soldiers for hire include Syrian and Libyan nationals, as well as other infantrymen recruited by the Wagner Group, a Russian-backed private military company, according to an unnamed European official cited in the report. The official estimated between 10,000 to 20,000 mercenaries are involved in Russia’s new offensive in eastern Ukraine.