U.S. Defense Secretary Lloyd Austin said Wednesday there is evidence that North Korea has sent troops to Russia, as South Korea’s spy chief told lawmakers that 3,000 North Korean troops are in the country receiving training on drones and other equipment before being deployed to battlefields in Ukraine.

Secretary of Defense Lloyd Austin said North Korea has deployed troops to Russia, the first senior US official to confirm the development on the record, as North Korea and Russia have forged increasingly friendly ties since Moscow’s invasion of Ukraine.