For years, North Korea has rattled the world with its nuclear tests and its threats to visit a nuclear holocaust upon the United States. Now, the finding by the Malaysian police that Kim Jong-nam was assassinated with VX nerve agent is a stark reminder of the North’s lesser-known weapons of mass destruction: a stockpile of chemical and biological weapons.

Mr. Kim, the estranged elder brother of North Korea’s leader, Kim Jong-un, was killed on Feb. 13 when two women rubbed his face with the nerve agent at Kuala Lumpur International Airport, the police said on Friday.

If North Korean citizens were behind the killing, as Malaysian officials suggest, the use of VX raises several questions: Was the North Korean government using the attack to signal to the world its fearsome arsenal of such dangerous weapons? Or was the toxin simply an attempt to avoid detection in carrying out a brazen killing at one of the world’s busiest airports?

… “By using VX in an international airport in the heart of Asia, North Korea has sent a very clear message to the world that it will strike its enemies anywhere in the world,” said Rohan Gunaratna, an expert on terrorism at the S. Rajaratnam School of International Studies in Singapore. “It also demonstrates the North Korean response in the event of an attack against North Korea.”