Update: According to a U.S. government source speaking to Reuters, the U.S. strongly believes that North Korean agents murdered the estranged half-brother of North Korean leader Kim Jong Un in Malaysia. This, even though U.S. authorities have not yet determined exactly how Kim Jong Nam was killed, according to the source, who did not provide firm evidence to support the government's conclusion.

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Just two days after North Korea embarrassed both the US and Japan by test-firing a new, nuclear-capable ICBM with a 2000 mile range, with neither Trump nor Abe able to articulate a clear retaliation strategy, moments ago Yonhap news agency reported that the elder half-brother of North Korean leader Kim Jong Un has been assassinated at Kuala Lumpur airport.

Kim Jong Nam

Kim Jong Nam, 45, who had lived outside North Korea for years, was reported to have been killed by poison needle by two women who fled the scene by taxi, the reports said.

Police official Fadzil Ahmat said the cause of Kim's death was not yet known, and a post mortem would be carried out on the body. "So far there are no suspects, but we have started investigations and are looking at a few possibilities to get leads," Fadzil told Reuters.

According to Fadzil, Kim had been planning to travel to Macau on Monday when he fell ill at the low-cost terminal of Kuala Lumpur International Airport (KLIA). "The deceased ... felt like someone grabbed or held his face from behind," Fadzil said. "He felt dizzy, so he asked for help at the ... counter of KLIA."

Kim was taken to an airport clinic where he still felt unwell, and it was decided to take him to hospital. He died in the ambulance on the way to Putrajaya Hospital, Fadzil added.

He was once considered to be the heir to late North Korean leader Kim Jong Il but he fell out of favor with his father in 2001 after he was caught trying to enter Japan on a false passport, and was arrested at Tokyo airport, apparently en route to Disneyland. Kim Jong Nam had been critical of Kim Jong Un, reportedly saying in 2012 that he “won’t last long” because of his youth and inexperience. The two brothers have different mothers, Bloomberg reports. Kim Jong Nam did not attend his father's funeral in 2011.

Kim Jong Nam said several times over the years that he had no interest in leading his country. "Personally, I am against third-generation succession," he told Japan's Asahi TV in 2010. "I hope my younger brother will do his best for the sake of North Koreans' prosperous lives."

His cousin, Lee Han-young, who defected to South Korea through Switzerland in 1982, was shot and killed by North Korean agents in Seoul in 1997, according to South Korea. Kim Jong Nam's mother was an actress named Song Hye Rim.

"My father was keeping highly secret the fact that he was living with my mother who was married, a famous movie actress, so I couldn’t get out of the house or make friends," Kim Jong Nam was quoted as saying in a 2012 book by a Japanese journalist. "That solitude from childhood may have made me what I am now, preferring freedom."

According to Reuters, South Korea's foreign ministry said it could not confirm the reports, and the country's intelligence agency could not immediately be reached for comment.

"We don't know if there was a cloth or needles; the receptionist said someone grabbed his face, he felt dizzy," police official Fadzil said, when asked about the nature of the reported attack. Malaysia is one of a dwindling number of countries that has close relations with North Korea, which is under tightening global sanctions over its nuclear tests and ballistic missile launches, the latest of which took place on Sunday.

So who may be behind the murder? As BBG adds, Kim has carried out a series of executions since taking power in 2011, the most high profile of which was the 2013 killing of his uncle and one-time deputy Jang Song Thaek. If Kim Jong Nam was killed by a North Korean spy, it indicates that Kim Jong Un felt a sense of paranoia about his own future and wanted to remove any potential successors, according to Namkoong Young, who has been teaching inter-Korean politics at Hankuk University of Foreign Studies for more than 25 years.

“Jong Nam has been in exile for years away from North’s politics for a long time but he is still the eldest son of Kim Jong Il,” Namkoong said. “And if there was any move or plan by some elite there to have him replace Jong Un, he probably should be removed.”

Of course, it is just as likely that a certain spy agency could have staged the murder, making it seem like it was preemptive retaliation by Un. For now there are no further details.

A person in the Malaysian prime minister’s office, who did not want to be named, confirmed that a North Korean national had been killed at the airport and taken to hospital. The person said police were still waiting for the autopsy report. South Korean officials have yet to comment publicly on the matter. Malaysia’s foreign ministry is still waiting for information from the police on the identity of the deceased man. The death is under the purview of the home affairs ministry, she said. The police didn’t immediately respond to a request for comment.

In 2014, Kim Jong Un had about 50 officials executed on charges ranging from graft to watching South Korean soap operas. Two senior officials were executed with an anti-aircraft gun in August last year on Kim’s orders, South Korea’s JoongAng Ilbo newspaper reported, citing people it did not identify.