In a case with a thousand plot twists, there has been but one constant in the murder investigation of Kim Jong Nam: Nothing is ever what it seems.

The victim himself — the playboy half brother of North Korean leader Kim Jong Un — was traveling under false papers when he died and had to be identified using DNA. The two women accused of killing him turned out to be hired dupes, paid a few dollars to perform what they thought was a reality-TV stunt.

Stranger still was the murder weapon, liquid VX, a toxin so powerful that a few drops rubbed onto the skin killed the victim in minutes, yet it failed to harm the two women who applied the poison with their bare hands. Even more mysterious: why North Korea would go to extravagant lengths to use a battlefield-grade chemical weapon on foreign soil, only to work equally hard to cover its tracks.

For the prosecutors preparing for the first court hearings later this month, some of the mysteries behind Kim Jong Nam’s death inside a Malaysian airport terminal will likely never be resolved. But nearly five months after the killing, U.S. and Asian officials have a clearer view of the attack’s significance. In carrying out history’s first state-sponsored VX assassination in a country 3,000 miles from its borders, North Korea has demonstrated a new willingness to use its formidable arsenal of deadly toxins and poisons to kill or intimidate enemies on foreign soil, analysts say.

Seen in the light of North Korea’s recent flurry of provocative missiles tests, Kim Jong Nam’s killing now looks to many experts like a proving exercise for a weapons system — in this case, a robust chemical-weapons stockpile that Pyongyang is thought to have built over decades and kept carefully under wraps.

“The choice of weapons was not accidental,” said Sue Mi Terry, a former senior analyst on North Korea at the CIA and currently managing director for Korea at the Bower Group Asia. “Everything about this incident was intended to send a message.”

U.S. and South Korean intelligence agencies have long believed that North Korea possesses significant stores of the nerve agents VX and sarin — and probably biological weapons as well — but in the past, such arsenals were assumed to be intended as a deterrent against foreign attacks. But in the attack on Kim Jong Nam, North Korea revealed a strategy for using chemicals that looks a lot like ­cyberwarfare: limited, highly secretive attacks that can damage an enemy without inviting massive retaliation. Continue reading.