North Korea's main goal is said to be dominance over the whole peninsula.

The rogue state's tested a hydrogen bomb, which rocked the country with a 5.2 magnitude shake.

Korea expert at Tufts University in the US, Sung-Yoon Lee, told Mike Hosking it's part of a bigger plan for the country.

"North Korea needs to be a menace, needs to be a credible threat to the United States in order to get the US to perhaps one day abandon South Korea."

He said dominance over the south is a non-negotiable goal for North Korea.

LISTEN ABOVE AS SUNG-YOON LEE SPEAKS WITH MIKE HOSKING