SAN FRANCISCO (AP/CBS) — South Korea’s Yonhap news agency says two quakes were detected near North Korea’s nuclear test site.

The U.S. Geological Survey called the first quake an explosion with a magnitude 6.3. The second quake measured 4.6.

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South Korea’s military said earlier Sunday that North Korea is believed to have conducted its sixth nuclear test after it picked up seismic waves measuring 5.6.

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It came hours after North Korea claimed that its leader has inspected a hydrogen bomb meant for a new intercontinental ballistic missile.

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