BEIJING (NYTIMES) - After approving plans on Friday (Feb 24) for informal talks in New York between a North Korean delegation and former US officials, the Trump administration reversed course hours later, withdrawing approval for the North Koreans' visas, said two people who were to take part in the planned talks.

The schedule called for the two sides to meet in early March, and arrangements were underway for the six-member North Korean group, led by Choe Son Hui, who runs the US affairs bureau of the North's Foreign Ministry, to travel to New York.

The organiser of the talks, the National Committee on American Foreign Policy, led by Donald S. Zagoria, was told by the State Department on Friday morning that the visas would be granted.

But the decision was reversed in the afternoon when "someone overruled State," said one person who planned to participate in the talks. Both of the people on the participants' list spoke on the condition of anonymity because of the delicacy of the matter.

The reversal came as the Malaysian government announced that VX nerve agent, a chemical on a UN list of weapons of mass destruction, was used to kill Kim Jong Nam, the estranged half brother of the leader of North Korea, at Kuala Lumpur International Airport on Feb 13.

South Korea has accused North Korea's leader, Kim Jong Un, of ordering the killing.

Just days before Kim's death, North Korea launched a new type of nuclear-capable missile, apparently timed to coincide with the visit of Prime Minister Shinzo Abe of Japan to the United States.

News of the missile test arrived as President Donald Trump and Abe were eating dinner at Mar-a-Lago, the president's members-only club in Palm Beach, Florida.

At first, the North Korea developments did not appear to deter the State Department's plan to move ahead with the talks.

The use of the VX nerve agent was known when Zagoria got the green light about the visas Friday morning. The missile test was on Feb 11.

The State Department also knew about tough comments Trump made about the North Korean leader during an interview with Reuters on Thursday.

"It's very late," Trump said when asked whether he would meet with Kim. "We're very angry at what he's done, and frankly this should have been taken care of during the Obama administration."

The decision to reverse the initial approval for the visas came hours later on Friday afternoon, one of the people who planned to take part in the talks said.

But it was clear, that person said, that a senior official in the State Department, the White House or elsewhere in the government had second thoughts about issuing visas to representatives of North Korea in light of recent events.

"I suspect it was a combination of the VX attack and the president's personal pique that caused the reversal," the person said. "Someone obviously looked at the fact that the United States was going to issue visas to representatives of a country that had just violated international law, carried out a murder and intentionally violated the sovereignty of another country, and decided, 'Maybe this isn't such a good idea.'"

While the talks were unofficial, they were seen as a test of the willingness of the Trump administration to begin serious negotiations at a later date, or to send a special US envoy to North Korea.

Several prominent nuclear weapons experts have urged Trump to send an envoy, arguing that President Barack Obama's refusal to engage with the North allowed it to make significant advances in its nuclear weapons programme.

"Every six to seven weeks North Korea may be able to add another nuclear weapon to its arsenal," Siegfried S. Hecker, emeritus director of the Los Alamos National Laboratory and a senior fellow at the Center for International Security and Cooperation at Stanford University, said in a recent Op-Ed article.

The leader of the North Korean delegation, Choe, planned to travel to New York in her "nongovernmental" role as president of North Korea's Institute for American Studies.

The American participants were mostly former officials who had dealt with North Korea over many years. Some of them have participated in similar gatherings with North Koreans organized outside the United States.

But more weight was given to the New York gathering because it was taking place at the start of the new administration. During his election campaign, Trump said he was open to meeting with the North Korean leader over a hamburger.

The Americans in the group represented a wide range of views on North Korea. Winston Lord, a former ambassador to China who was on the list of participants, recently wrote in a dissent to a report for the Asia Society that the United States should immediately step up sanctions on North Korea.

Others in the US delegation were Robert L. Gallucci, a negotiator on North Korea during the Clinton presidency; Victor Cha, a senior adviser on North Korea to George W. Bush; and Evans J.R. Revere, a former principal deputy assistant secretary of state specializing in North Korea.

Gallucci and Cha wrote a report for the George W. Bush Institute last year that emphasized the human rights abuses in North Korea.

As well as holding discussions about the North's rapidly expanding nuclear program, the US delegation was planning to talk with the North Koreans about two Americans detained in North Korea.