WASHINGTON (BLOOMBERG) - United States President Donald Trump brushed off news of a possible weapons test by North Korea, vowing that leader Kim Jong Un “will do nothing to interfere” and that a denuclearisation deal with the US “will happen”.

Saturday’s (May 4) tweet, posted while Mr Trump was in a motorcade to the Trump National Golf Club in Virginia, was the President’s first response to news overnight that Pyongyang had fired numerous short-range projectiles off its eastern coast on Saturday, according to South Korean authorities.

The move was seen as Mr Kim’s latest and most provocative signal of frustration over talks with Mr Trump following the pair’s failed summit in Vietnam in February.

The significance of the test was difficult to assess as South Korea revised its account of the nature and scale of the weapons discharged from the eastern port of Wonsan just after 9am Saturday local time.

After first calling them “missiles”, South Korea’s Joint Chiefs of Staff later changed its description to “projectiles”, saying greater clarity would require more analysis.

The details are key since Mr Trump has cited Mr Kim’s self-imposed freeze on missile and nuclear weapons tests to support his decision to continue negotiations with the North Korean leader.

South Korea’s descriptions of the incident suggested shorter-range rockets or artillery that would be less likely for the US to interpret as a violation of Mr Kim’s pledge to refrain from testing.

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“We are aware of North Korea’s actions tonight. We will continue to monitor as necessary,” White House Press Secretary Sarah Sanders said.

National Security Adviser John Bolton briefed the President about the launch, according to a senior administration official, who asked for anonymity to discuss the matter.

The weapons were fired from the Hodo Peninsula, which has been the site of past live-fire artillery exercises, and travelled 70km to 200km, the joint chiefs said earlier on Saturday.

The Yonhap News Agency later reported that the weapons fired were “not missiles”, citing unidentified lawmakers briefed by intelligence officials.

“Missiles are projectiles, but South Korea’s Joint Chiefs of Staff might be using ‘projectile’ to imply an unguided rocket, like one of North Korea’s older rocket artillery systems,” said Mr Ankit Panda, an adjunct senior fellow at the Federation of American Scientists.

“This could also be a politicised attempt to make the word ‘missile’ not so prominent, in case that creates the kind of news cycle that Trump doesn’t want.”

The weapons test was nonetheless Mr Kim’s most significant provocation since he launched an intercontinental ballistic missile in November 2017, declared his nuclear weapons programme “complete” and opened talks.

Anything in this very interesting world is possible, but I believe that Kim Jong Un fully realizes the great economic potential of North Korea, & will do nothing to interfere or end it. He also knows that I am with him & does not want to break his promise to me. Deal will happen! — Donald J. Trump (@realDonaldTrump) May 4, 2019

South Korea President Moon Jae-in’s spokesman condemned the incident, saying in a statement that they “go against” a military agreement the two Koreas reached in September to halt “hostile activities”.

Mr Kim has expressed increasing frustration since Mr Trump refused his demands for sanctions relief and walked out of their second summit in Hanoi in February.

After a year of talks, Mr Kim has made only a pledge to “work towards complete denuclearisation of the Korean peninsula”, without defining the phrase.

The North Korean leader accused the US of “bad faith” during a meeting with Russian President Vladimir Putin in Vladivostok last week.

He had earlier told North Korea’s Supreme People’s Assembly that he would wait “with patience till the end of this year” for the US to make a better offer.

A shorter-range test could also signal displeasure with South Korea’s participation in joint military drills with the US, despite Mr Trump’s decision to scale down those exercises.

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North Korean state media has repeatedly complained about the drills in recent weeks and Mr Kim pledged “corresponding acts” during his speech last month to the rubber-stamp Parliament.

South Korean Foreign Minister Kang Kyung-wha discussed Saturday’s incident with US Secretary of State Michael Pompeo by phone, the ministry said in a statement.

Nuclear envoy Lee Do-hoon made a separate call to US Special Representative Stephen Biegun, who is slated to visit Japan and South Korea next week.

“This is an expected move from North Korea – not too provoking, but urging the US to take a slightly stronger stance than their initial one,” said Professor Kim Hyun-wook, of the Korean National Diplomatic Academy.

“This seems like a message for Stephen Biegun’s planned trip to the peninsula.”

Japan’s Defence Ministry said on Saturday that the country had not detected any missiles entering its exclusive economic zone and, hence, there was no immediate impact to its national security.

Although Saturday’s launch was the most significant since Mr Kim’s detente with Mr Trump, North Korea has announced more limited weapons tests in recent months.

Mr Kim personally oversaw the test-firing of a “new-type tactical guided weapon” last month, which South Korea later said appeared to be a system intended for ground combat and not a ballistic missile.

Descriptions of the current incident suggested weapons ranging from rocket-propelled artillery to multiple rockets fired from launchers, analysts said.

Firing such a weapon could serve a range of goals from pushing back against South Korea, to reassuring Mr Kim’s domestic audience of his leadership.

“The range they have would only be really good for hitting targets across the border in South Korea,” said Mr Nathan Hunt, an independent defence researcher.

“It could be seen that this was a signal to the ROK that the DPRK is losing patience,” he said, referring to South Korea’s and North Korea’s formal names.