Kim Jong-Un has vowed to make North Korea the "world's strongest nuclear power", state media reported Wednesday, as the reclusive nation shows little sign of reining in a weapons programme fuelling global alarm.

In a speech to workers behind the recent test of a new missile Pyongyang said was capable of reaching the United States, the North Korean leader declared Tuesday that his country "will victoriously advance and leap as the strongest nuclear power and military power in the world", according to state news agency KCNA