"In their messages, the Vietnamese leaders wrote: "Viet Nam and the Russian Federation (the former Soviet Union) officially established their diplomatic ties on Jan. 30, 1950, creating a foundation for the traditionally friendly and cooperative relations between the two countries for the last half of century."
Notice that "Russia" and the Vietnamese Communists see no break in solidarity from the time the USSR originally established diplomatic ties until now. "Russia" is not the Russia of old, it's just another (shell) name for the Soviet Union.