Ri Sung-kuk replaces his predecessor Kim Myong-gil, who returned to Pyongyang in April 2019. The post had remained vacant since then.
His appointment and arrival at the overseas mission came after Ri Ryong-nam was appointed as ambassador to China in 2021.
Vietnam's Foreign Ministry welcomed Ri, expressing hopes for closer relations between the two countries.
North Korea is also set to send new envoys to Romania and Singapore, signaling that the country is resuming its diplomatic engagement.
