The assassination of Kim Jong Nam in Kuala Lumpur airport last month is a reminder of the depravity and barbarity of his half-brother, North Korean ruler Kim Jong Un, and the world's most closed, and most cruel, dictatorship.

That he was murdered was not a surprise — it was well-known that Kim Jong Nam was a marked man and attempts had been made before. After Kim Jong Un killed his uncle, Jang Song Thaek, in late 2013, it was recognized that he would stop at nothing to eliminate perceived threats to his power, even his own relatives. But that Kim Jong Nam was killed so publicly, in an airport using female assassins and a highly toxic nerve agent, known as VX, is brazen in the extreme. The United Nations classifies VX as a weapon of mass destruction.

It is still difficult to know whether the assassination was specifically timed for a particular political reason, or whether it was opportunistic, taking advantage of Kim Jong Nam's particular vulnerability at that moment. But that it was ordered by Pyongyang is hardly in doubt now — the behavior of North Korean officials since the murder suggests their involvement. The desperate attempts to have the corpse returned to North Korea before any autopsy, the diplomatic row that ensued with Malaysia, and the attempted break-in at the morgue all point to efforts at a cover-up by this criminal regime.