North Korea Goes Dark: Mystery as Kim Jong-Un Refuses To Answer Biden's Calls
Mr Biden's administration has begun a behind-the-scenes push to start talks with Pyongyang in February but is yet to receive any response. Supreme Leader Kim Jong-un has also not congratulated Mr Biden on his presidential win weeks after his inauguration.
Professor Sung-Yoon Lee, a leading North Korean expert at The Fletcher School of Law and Diplomacy at Tufts University, said: "North Korea is a serial proliferator.
"This is a long and very close partnership between North Korea and Iran.
"We know that North Korea and Iran are united in common factors or ideological hostility toward the United States."