Kim Jong-un may be obese, but he is no fool when it comes to guarding his flank.  You just can't be too careful when watching your back if you are a murderous dictator.  He believes in killing off any possible rivals before they can act against him.  He already had an uncle executed, and now a potential rival, the actual firstborn child of his father, has been executed in exile.

ZeroHedge reports:

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, 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.

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.

The last point about different mothers is key.  The mothers are serious rivals, and rivalry readily gets murderous at the level of absolute monarchy.

There is no way of knowing if Kim got rumor of a plot against him, nor of the nature of such a plot.  But he is ruthless.

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.

I don't think it is just as likely at all.  And the name is Kim, not Un.

One thing about the two Kim half-brothers: they do put on the kilograms: