North Korean leader Kim Jong Un observed the successful test of an unspecified “newly developed ultramodern tactical weapon,” state media has reported, in an apparent bid to apply pressure on the United States and South Korea.

It did not appear to be a test of a nuclear device or a long-range missile with the potential to target the US.

A string of such tests last year had many fearing war before the North turned to engagement and diplomacy.

Still, any mention of weapons testing could influence the direction of stalled diplomatic efforts spearheaded by Washington and aimed at ridding the North of its nuclear weapons.

The North has not publicly tested any weapons since November 2017, but in recent days Pyongyang reportedly expressed anger at US-led international sanctions and ongoing small-scale military drills between South Korea and the United States.

South Korea North Korea Weapon TestSouth Korean army soldiers patrol by the national flags attached on the barbed-wire fence at the Imjingak Pavilion, near the border with North Korea (Ahn Young-joon/AP)

Earlier this month, North Korea’s Foreign Ministry warned it could bring back its policy of bolstering its nuclear arsenal if it does not receive sanctions relief.

“It’s North Korea-style coercive diplomacy. North Korea is saying ‘If you don’t listen to us, you will face political burdens’,” said analyst Shin Beomchul of Seoul’s Asan Institute for Policy Studies.

Diplomacy has stalled since a summit between Mr Kim and US president Donald Trump in June, with Washington pushing for more action on nuclear disarmament and the North insisting that the US first approve a peace declaration formally ending the Korean War and lift sanctions.

Mr Shin said the weapon North Korea tested could be a missile, artillery, an anti-air gun, a drone or other high-tech conventional weapons systems.

Yang Wook, a Seoul-based military expert, said a “tactical weapon” in North Korea refers to “a weapon aimed at striking South Korea including US military bases” there, so the North may have tested a short-range missile or a multiple rocket launch system.

Even if the test was a message for Washington and Seoul, Friday’s report from the North was noticeably less belligerent than past announcements of weapons tests, and did not focus on North Korean claims of US and South Korean hostility.

Mr Yang said the latest North Korean test will not completely break down nuclear diplomacy, though more questions would be raised about how sincere the North is about its commitment to denuclearisation.

North Korea Weapon TestNorth Korean leader Kim Jong Un listens to a military official as he inspects a weapon testing at the Academy of National Defence Science (Korean Central News Agency/Korea News Service via AP)

Asked about the test, the US State Department said that American and North Korean officials are talking about implementing the commitments that Mr Trump and Mr Kim made during their June meeting in Singapore.

Eugene Lee, spokeswoman of South Korea’s Unification Ministry, declined to comment on Mr Kim’s inspection of the weapons test.

US vice president Mike Pence, attending a Southeast Asian summit in Singapore, cited the “great progress” made on North Korea but said more had to be done.

A year and a half ago, “nuclear tests were taking place, missiles were flying over Japan and there were threats and propagations against our nation and nations in the region,” Mr Pence said.

“Today, no more missiles are flying, no more nuclear tests, our hostages have come home, and North Korea has begun anew to return fallen American heroes from the Korean War to our soil. We made great progress but there’s more work to be done,” he said.

Mr Pence stressed that UN sanctions had to remain enforced.

It is the first publicly known field inspection of a weapons test by Kim Jong Un since he observed the testing of the Hwasong-15 intercontinental ballistic missile in November of last year, according to South Korea’s Unification Ministry.

The North said the test took place at the Academy of National Defence Science and that Mr Kim could not suppress his “passionate joy” at its success.

He was described as “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.”

Last year’s string of increasingly powerful 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.

Mr Trump and Mr Kim are both interested in another summit, but it is unclear when it might happen.

Mr Pence has said the next meeting would allow the two leaders to put what they discussed in their last summit on paper.