Russian leader Vladimir Putin asserted that his country will expand its “comprehensive and constructive bilateral relationship” with North Korea in a letter to Kim Jong Un, DPRK state media reported Monday, weeks after Pyongyang recognized Moscow-backed breakaway republics in eastern Ukraine.

Putin added that strengthened ties will benefit “the safety and stability of the Korean peninsula and the Northeast Asian region as a whole,” exchanging letters with Kim to mark the holiday celebrating Korea’s liberation from Japanese colonial rule.

In his response, Kim Jong Un thanked Putin and wrote that strategic and tactical cooperation between the two countries has reached