North Korean leader Kim Jong Un observed the successful test of a "newly developed high-tech tactical" weapon though it was unclear what sort of armament it was.

The viewing on Friday didn't appear to be a nuclear or missile-related test, a string of which last year had many fearing war before the North turned to engagement and diplomacy early this year.

Still, any mention of weapons testing could influence the direction of stalled diplomacy between Washington and Pyongyang that's meant to rid the North of its nuclear weapons.

The North said the test took place at the Academy of National Defence Science and Kim couldn't suppress his "passionate joy" at its success.
"Supreme Leader Kim Jong Un was so excited to say that another great work was done by the defence scientists and munitions industrial workers to increase the defence capability of the country," the Korean Central News Agency reported.

The weapon was conceived by Kim's deceased father and the new leader "missed Kim Jong Il very much while seeing the great success of its test", state-run KCNA said.

It was Kim's first field visit to a testing site since his unprecedented summit with US President Donald Trump in June, when the two leaders agreed to work towards denuclearisation and peace on the Korean Peninsula, and to establish new relations between the United States and North Korea.

Any testing of new weapons is likely to raise tensions with Washington, which has said there will be no easing of international sanctions until North Korea takes more concrete steps to abandon its nuclear weapons or long-range missiles.

The White House referred questions about the latest development to the State Department, which did not immediately respond to a request for comment.

The North has reportedly expressed anger in recent days at South Korea's resumption of small-scale military drills with the United States. But Friday's report didn't appear to focus on North Korean claims of US and South Korean hostility - as it did when announcing previous weapons tests.

Last year's weapons tests, many experts believe, put the North on the brink of a viable arsenal of nuclear-tipped missiles that can target anywhere in the mainland United States.

Diplomacy has stalled since the June summit between Trump and Kim in Singapore, with Washington pushing for more action on nuclear disarmament and the North insisting the US first approve a peace declaration formally ending the 1950-53 Korean War.

Professor Yang Moo-jin, from the University of North Korea Studies in Seoul, South Korea, said Friday's test was "a signal to the US sent ahead of the high-level talks that its own patience is also wearing thin".