Seoul, South Korea — Russia’s foreign minister warned the U.S., South Korea and Japan against forming a security partnership targeting North Korea as he visited his country's ally for talks on further solidifying their booming military and other cooperation.

South Korea, Japan and the United States conducted a joint air drill on Friday involving a U.S. B-52 strategic bomber and fighter jets of the three allies over international waters, the South's defence ministry said.

Relations between Russia and North Korea have flourished in recent years, with North Korea supplying troops and ammunition to support Russia's war against Ukraine in return for military and economic assistance.