"Regarding which measures to take, I don't really know since it is what Kim Jong-un does", Ri said.
"Whatever Trump may have expected, he will face results beyond his expectation", Kim said.
The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) said that it detected two seismic events in North Korea, but they were "unlikely (to have been) man-made".
"After taking office, Trump has rendered the world restless through threats and blackmail against all countries in the world", Kim said.
North Korean Foreign Minister Ri Yong-ho said in NY on Thursday hat Pyongyang may consider its most powerful test of a hydrogen bomb over the Pacific Ocean.
If North Korea follows through on its latest threat of setting off a nuclear explosion over the Pacific Ocean, it will ultimately be up to President Trump whether the United States will respond with military action, Secretary of State Rex Tillerson told ABC News on Friday.
To note, this is not the first time the U.S. President was called a dotard.
China wants to stop North Korea's nuclear and missile development but has warned against pushing the government of Kim Jong Un so hard it collapses or hurting ordinary North Koreans.
"That would be a disaster beyond compare for the region, for the people of North Korea, who have no dog in this fight, who are just trying to feed themselves", Australia's Deputy Prime Minister Barnaby Joyce told reporters in Perth.