A malfunctioning South Korean ballistic missile blew up as it ploughed into the ground on Wednesday during a live-fire drill with the United States that was a reprisal for North Korea’s successful launch a day earlier of a weapon that flew over Japan and has the range to strike the US territory of Guam.

The explosion and subsequent fire panicked and confused residents of the coastal city of Gangneung, who were already uneasy over the increasingly provocative weapons tests by rival North Korea. Their concern that it could be a North Korean attack only grew as the military and government officials provided no explanation about the explosion for hours.