Monday's official media reports that Russian President Vladimir Putin informed North Korean leader Kim Jong-un that the two countries will "expand the comprehensive and constructive bilateral relations through joint efforts."

North Korea's KCNA news agency reported that in a letter to Kim for Korea's independence day, Putin stated that tighter ties would be in both countries best interests and would assist boost the security and stability of the Korean peninsula and the Northeast Asian area.

Kim also addressed a letter to Putin stating that the friendship between Russia and North Korea was created during World War II with the triumph over Japan, which had controlled the Korean peninsula.

Kim wrote in the letter that "strategic and tactical cooperation, support, and solidarity" between the two countries had reached a new level in their efforts to thwart threats and provocations from hostile military forces. The opposing troops were not identified by KCNA, although the term is often used to refer to the United States and its allies.

Kim projected that cooperation between Russia and North Korea would increase in 2019 due to an agreement reached that year.

North Korea acknowledged two Russian-backed breakaway "people's republics" in eastern Ukraine as sovereign governments in July, and authorities broached the possibility of sending North Korean personnel to the territory to assist with construction and other labor.

Ukraine, battling a Russian invasion dubbed by Moscow as a "special military operation," broke ties with Pyongyang immediately in response to the move.