North Korea is looking to step up its military cooperation with Russia by sending Moscow new types of tactical guided missiles, while Pyongyang may soon conduct fresh tests of its own missiles designed to deliver nuclear strikes, South Korea’s defense minister said.

Kim Jong Un’s regime appears to be planning for a trial of atmospheric re-entry of a warhead designed to be carried by an intercontinental ballistic missile to the U.S. mainland, Shin Wonsik said in an exclusive interview with Yonhap News published Thursday. This would mean firing a long-range rocket a distance of several thousand kilometers, he said.

The cooperation outlined by Shin would mark a new phase of Kim’s assistance for Russian President Vladimir Putin in his war on Ukraine, which could help the Kremlin continue its grinding bombardment of its neighbor.