White House analysis casts doubt on North Korea's nuclear test claims
North Korea says it has successfully conducted a test of a miniaturised hydrogen nuclear device on Wednesday morning.
However, the White House has said initial analysis of the reported nuclear test is not consistent with claims of a successful hydrogen bomb.
In a statement the country said it would continue to strengthen its nuclear programme as long as the US maintained what it called "its stance of aggression."
Much of the international community has condemned North Korea after the claim, including China, the country's major ally, and Britain, which said the move was a "provocation".