THE standoff between North Korea and the West continues to bedevil the otherwise relatively stable Asia-Pacific region and spook global markets. The crisis took a turn for the worse when Pyongyang detonated over the weekend what it said was a hydrogen bomb that could be mounted on a missile.

It was North Korea’s sixth and most powerful weapons test, in defiance of the United Nations Security Council. It further raised the stakes and sent Seoul into a war-games mode, with the South Korean military firing ballistic missiles on Monday to simulate an attack on nuclear test sites used by Pyongyang.