South Korea's defense minister said on Wednesday he sees a high possibility of North Korea conducting a sixth nuclear test in the wake of the North's first test-launch of an intercontinental ballistic missile.

"North Korea's eventual goal is to weaponise its nuclear power, so I see a high chance that will happen," Defense Minister Han Min-koo told a parliamentary briefing in response to a question from a lawmaker about whether he believed North Korea would conduct a nuclear test soon.

"We know they're always prepared to conduct nuclear tests but so far we have not detected any unusual signs," Han said.

North Korea said it tested a newly developed intercontinental ballistic missile on Tuesday, which some experts believe had the range to reach parts of the mainland United States.