U.S. and South Korean officials say there’s evidence that North Korea has dispatched troops to Russia in a potential escalation of a nearly 3-year-old war with Ukraine

The United States, South Korea, Britain and Ukraine say North Korea has sent troops to Russia for possible deployment in Ukraine, a move that the White House said on Wednesday is in violation of United Nations Security Council resolutions.

The Biden administration said that at least 3,000 North Korean troops are training in Russia, though it remains unclear if they’ll join the war.

Some 12,000 North Korean troops will be sent to Russia, a key United States ally said Thursday, vowing it “will not stand by and do nothing” in the face of this significant “provocation.”