Malaysian police investigating the death of Kim Jong Nam — the half-brother of North Korean dictator Kim Jong Un — after he was attacked at Kuala Lumpur Airport on Feb. 13 say they want to speak with a North Korean diplomat and a staff member of North Korea’s state-owned airline Air Koryo. However, the North Korean Embassy is reportedly not cooperating.

The announcement reinforces suspicions that Kim Jong Nam was assassinated on the orders of his estranged younger sibling, who may have feared the elder Kim was a political threat to his leadership of a country that has seen two dynastic successions. Two women can be seen on security camera footage holding a cloth over Kim Jong Nam’s face at the terminal, after which the 45-year-old began to feel ill. He eventually died en route to hospital.

According to Professor Steven Weber, a North Korea expert at the University of Berkeley, California, “There have been no credible signals that the story is anything other than what it appears to be.”

He adds: “Whether this was an opportunistic move, or whether it was planned because China was more concerned with issues in the South China Sea and with the Americans, so maybe North Korea could get away with it now, it’s really, really hard to tell.”

The two women — one Vietnamese and one Indonesian — have been detained along with one North Korean and one Malaysian man. The Indonesian woman has claimed that she thought she was participating in an innocent prank when she approached Kim Jong Nam; however, this claim was rubbished by Malaysia’s police chief Khalid Abu Bakar on Wednesday.

“The lady was moving away with her hands towards the bathroom,” he told reporters. “She was very aware that it was toxic and that she needed to wash her hands.”

Four other North Koreans, whom Khalid suspects of being “heavily involved” with the assassination, fled Malaysia in the hours after Kim Jong Nam’s death. Should the embassy refuse to cooperate regarding the diplomat and Air Koryo staff member also being sought — identified respectively as Hyon Kwang Song and Kim Uk Il, then: “We will compel them to come to us,” Khalid said.

The results of an autopsy on Kim Jong Nam are still pending, though officials have revealed there are no signs of a heart attack or puncture wounds. In yet another twist, security has been beefed up at the mortuary holding his body after an attempted break-in, says Khalid.

North Korea’s Ambassador to Malaysia, Kang Chol, has demanded Kim Jong Nam’s body be returned, accusing Kuala Lumpur of “unjust behavior” and dismissing the police investigation as politically motivated. Malaysian Prime Minister Najib Razak slammed the Ambassador’s statement as “totally uncalled for.” “It was diplomatically rude,” Najib said, “but Malaysia will stand firm.”

It remains to be seen whether the fallout from Kim Jong Nam’s death will have wider implications for East Asia’s security dynamic. On Sunday, China suspended coal imports from North Korea in what appeared to be a direct response to Kim Jong Nam’s murder (even if that was denied by Chinese state media).

Kim Jong Nam lived mostly in the semiautonomous Chinese territory of Macau and was seen as close to the Chinese leadership, which may have been eyeing him in case regime change in Pyongyang was deemed desirable and the need arose for a pliant puppet to replace the erratic Kim Jong Un. And yet, “Some people say Kim Jong Nam was under the protection from China, but that’s only speculation,” says Hu Jiping, a researcher at Chinese Institute of Contemporary International Relations.

According to William Choong, Asia security specialist at the International Institute for Strategic Studies in Singapore, Chinese anger at Kim Jong Nam’s assassination is likely only “one of the factors” that would have prompted the coal moratorium. “But we have to see it in the wider context of trying to restart talks and restraining [North Korea] in its missile tests,” he says.

China’s overwhelming strategic goal will be to keep the North Korean state functioning, given that its collapse would likely see a flood of refugees into northeastern China and a unified and U.S.-allied Korean peninsular ruled from Seoul.

However, Pyongyang’s continued nuclear and missile tests — the latest on Feb. 11 — increase pressure on Beijing and have also led to Seoul’s decision to deploy the U.S.-backed THAAD missile defense system, which Beijing deems an affront.

“The Chinese would like the situation to remain the status quo,” says Webber. “So it can’t turn the screws so tightly [as to provoke] a collapse of the North Korean regime.”

Beijing has long pushed for a resumption of the six-party denuclearization talks — comprising North and South Korea, Japan, Russia, China and the U.S. — which ran from 2003 to 2009 before being nixed by Kim Jong Il, father to both Kim Jong Un and Kim Jong Nam.

The coal freeze may be designed to prod North Korea and the U.S. back to the negotiating table. Last weekend, Chinese Deputy Foreign Minister Fu Ying met new U.S. Secretary of Defense James Mattis at the Munich Security Conference. On Monday, the Washington Post reported that preparations were under way for North Korean officials to come to New York City for talks with former U.S. officials — the first such discussions since July 2011.

However, analysts say Kim Jong Un believes nuclear capability to be an equalizer that guarantees the survival of his regime, and that the 33-year-old is cognizant of the fates of Iraqi dictator Saddam Hussein and Libyan dictator Muammar Gaddafi, who were both toppled after abandoning their pursuit of atomic weapons.

One option broached by academic John Delury, professor of East Asian studies at Yonsei University in Seoul, is of a potential “double freeze” agreement. By which, Pyongyang would agree not to perform any more nuclear or missile tests and Washington would suspend its annual joint naval exercises with South Korea and put THAAD deployment under review.

“The most talks can achieve is a ‘double freeze,’” says Choong. “I don’t think unilateral disarmament is ever going to happen in our generation.”

A ‘double freeze’ would be the best possible scenario for Beijing, given its support for the North Korean state but opposition to its nuclear program and THAAD. “China advocates solving the problems through dialogue and negotiations,” says Hu. “But if North Korea goes too far, China will also impose sanctions.”

At the same time, it’s unclear weather U.S. President Donald Trump would agree to anything less than unilateral disarmament, given his robust criticism of the Obama administration’s deal with Iran over its nuclear program.

According to Webber, Washington likely believes that North Korea has already extracted every possible concession it deserves from the West. “I don’t think talks now would be a negotiation, but more like an ultimatum,” he says.

“Of course, with the Trump Administration you never really know.”

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Write to Charlie Campbell at charlie.campbell@time.com.