The White House has confirmed that North Korea deployed troops to Russia earlier this month.

National Security Council spokesperson John Kirby said Wednesday during a press briefing that the North moved at least three-thousand soldiers into eastern Russia between early and mid-October. 

Kirby said the U.S. believes these soldiers traveled by ship to Vladivostok in the Russian Far East and then traveled onward to multiple Russian military training sites in eastern Russia, where they are currently undergoing training.

The White House official said the U.S. does not yet know whether these soldiers will fight alongside the Russian military, but that it is “a highly concerning probability.”

Kirby added that they could go to western Russia and engage in combat against Ukrainian forces.

Earlier in the day, U.S. Defense Secretary Lloyd Austin said during a visit to Italy that there is evidence North Korea has sent troops to Russia.