SEOUL, South Korea (AP) — North Korea ratified a major defense treaty with Russia stipulating mutual military aid, the North’s state media reported Tuesday, as the U.S., South Korea and Ukraine say North Korea has sent thousands of troops to Russia to support its war against Ukraine.

The accord, signed by Putin and North Korean leader Kim Jong Un in June after a summit in Pyongyang, calls on each side to come to the other's aid in case of an armed attack. Russia's upper house ratified the treaty this week,

Russian President Vladimir Putin has signed off on a landmark defense pact with North Korea, a deal that comes amid reports that Pyongyang has dispatched thousands of troops to fight against Ukraine.