N.Korea's Kim oversees ICBM test

North Korean leader Kim Jong-un has pledged to counter US nuclear threats with nuclear weapons as he inspected a test of the country's new intercontinental ballistic missile, state media KCNA says.

The isolated country tested an intercontinental ballistic missile (ICBM) on Friday shortly after warning of "fiercer military responses" to Washington beefing up its regional security presence.

Attending the site with his daughter and wife, Kim said threats from the United States and its allies pursing a hostile policy prompted his country to "substantially accelerate the bolstering of its overwhelming nuclear deterrence".

"Kim Jong-un solemnly declared that if the enemies continue to pose threats ... our party and government will resolutely react to nukes with nuclear weapons and to total confrontation with all-out confrontation," KCNA said.

The launch of the Hwasong-17 ICBM was part of the North's "top-priority defence-building strategy" aimed at building "the most powerful and absolute nuclear deterrence," KCNA said, calling it "the strongest strategic weapon in the world".

The missile flew nearly 1000 kilometres for about 69 minutes and reached a maximum altitude of 6041km, KCNA said.

Japanese Defence Minister Yasukazu Hamada said the weapon could travel as far as 15,000km, enough to reach the continental United States.

On Thursday, North Korea's foreign minister, Choe Son Hui, denounced a trilateral summit on Sunday of the United States, South Korea and Japan, during which the leaders criticised Pyongyang's ongoing weapons tests and pledged greater security co-operation.

Choe singled out a recent series of their joint military drills and efforts to reinforce American extended deterrence, including its nuclear forces to deter attacks on the two key Asian allies.