Russian President Vladimir Putin said Russia and North Korea will expand bilateral relations, Pyongyang’s KCNA news agency reported on Monday, citing The Guardian.

Putin told Kim Jong-un that the two countries would “jointly expand comprehensive and constructive bilateral relations,” the quoted source said.

In a letter to Kim on the occasion of North Korea’s Liberation Day, Putin said that closer ties would be in the interests of both countries and help strengthen the security and stability of the Korean Peninsula and the Northeast Asian region.

In turn, Kim Jong-un sent Putin a letter in which he mentioned the Russian-Korean friendship that began in World War II with the victory over Japan.

Since then, “strategic and tactical cooperation, support and solidarity” between the two states have reached a new level in the joint fight against threats and challenges from the enemy’s armed forces, the letter also states.

KCNA did not name “hostile forces,” but the wording likely refers to the US and its allies.

Russia and North Korea signed a cooperation agreement in 2019 when dictator Kim Jong Un met with his Russian counterpart Vladimir Putin.

In July, North Korea recognized two so-called “people’s republics” occupied by Russians in eastern Ukraine, and officials said North Korean workers could be sent to those areas for reconstruction or other services.