SEOUL, South Korea — A seismic tremor was detected near an underground nuclear test site in North Korea on Sunday, prompting a scramble to determine if the North had conducted a sixth nuclear test in a direct challenge to President Trump.
If the North has tested another nuclear device, it would be an extraordinary show of defiance by North Korea’s leader, Kim Jong-un, against Mr. Trump, who has warned he would unleash “fire and fury” against North Korea if Pyongyang continued to threaten the United States with nuclear missiles.
South Korea’s Defense Ministry and Meteorological Administration said an “artificial” tremor with a magnitude of 5.6, detected at 12:36 p.m. local time, had emanated from the Punggye-ri underground nuclear test in northwestern North Korea. President Moon Jae-in of South Korea called an emergency meeting of his National Security Council in response to the report.
Analysts and officials have been warning that North Korea would conduct more nuclear and long-range missile tests, to master the technologies needed to build a nuclear warhead small and sophisticated enough to be fitted onto an intercontinental ballistic missile. Last week, South Korea’s National Intelligence Service told lawmakers in Seoul that North Korea was technically ready to conduct another nuclear test any time at Punggye-ri, where all its previous tests had taken place.