Update: North Korea has confirmed that it has "successfully tested a hydrogen bomb." The test was "an act of self-defense" against threats like the US.
A 5.1-magnitude earthquake detected near North Korea’s nuclear test site appears to have been artificial, according to South Korea’s meteorological service, raising the prospect the isolated regime tested a nuclear device. As Bloomberg reports, the "earthquake" follows North Korea’s threat in September that it is ready to use atomic weapons against the U.S. at any time and that its main nuclear facility was fully operational. The Pentagon is reportedly "looking into" the quake reports.