Any attack on Kim Jong Un’s regime — even a limited strike on weapons facilities — risks catastrophic blowback on some of Asia’s biggest economies. It could threaten to trigger a U.S. war with China and leave the capitals of allies South Korea and Japan at risk of destruction, the same calculation that has helped maintain an uneasy peace in North Asia since the Korean War in the 1950s.

“This has the potential to turn into a conflagration that Asia hasn’t seen since the Vietnam war,” said Brian Bridges, a Malaysia-based adjunct professor of Asian politics at Lingnan University in Hong Kong. “If anything, his unpredictability makes the situation more risky because the North Koreans aren’t 100 percent sure he won’t attack.”

Trump has sent warships near North Korea and threatened to act alone if necessary to prevent it from gaining the capability to strike the U.S. with a nuclear weapon. The unease has wiped $30 billion from South Korean equity values this week and driven a spike in the nation’s debt risk, as Kim shows signs of conducting another nuclear or ballistic-missile test.