Russian President Vladimir Putin spoke to North Korean leader Kim Jong Un reiterating that the two countries will expand bilateral relations with joint efforts.
Pyongyang's state media reported on Monday that Putin said closer ties would be in both countries' interests.
And would also help strengthen the security and stability of the Korean peninsula and the Northeastern Asian region.
North Korea's KCNA news agency also said Kim sent a letter to Putin saying Russian-North Korean friendship had been forged in World War II with victory over Japan, which had occupied the Korean peninsula.
Kim in the letter said, "The strategic and tactical cooperation, support and solidarity between the countries have since reached a new level in common efforts to frustrate threats and provocations from hostile military forces."
KCNA did not identify the hostile forces, but it has typically used that term to refer to the United States and its allies.