Hours after it announced developing a powerful hydrogen bomb, North Korea appeared to have tested two nuclear bombs Sunday, both triggering seismic shocks of earthquake proportions.
The first measured between 6.3 magnitude near its main test site, while the second test measured around 4.6 magnitude, according to Yonhap news agency, belonging to South Korea.
South Korea’s Joint Chiefs of Staff said in a statement that the first seismic tremor was detected near the North’s Punggye-ri test site.
United States Geological Survey recorded the magnitude at 6.3 — larger than any previous test.
Jana Pursely, a USGS geophysicist, told AFP: “It’s an explosion rather than an earthquake.”
Nuclear-armed Pyongyang has long sought the means to deliver an atomic warhead to the United States, its sworn enemy.
Questions remain over whether it has successfully miniaturised its weapons, and whether it has a working H-bomb, but the official Korean Central News Agency said before the quake that leader Kim Jong-Un had inspected such a device at the Nuclear Weapons Institute.
It was a “thermonuclear weapon with super explosive power made by our own efforts and technology”, KCNA cited Kim as saying, and “all components of the H-bomb were 100 percent domestically made”.
Pictures showed Kim in black suit examining a metal casing, with a shape akin to a peanut shell.
North Korea triggered a new ramping up of tensions in July, when it carried out two successful tests of an ICBM, the Hwasong-14, which apparently brought much of the US mainland within range.
It has since threatened to send a salvo of rockets towards the US territory of Guam, and last week fired a missile over Japan and into the Pacific, the first time time it has ever acknowledged doing so.
US President Donald Trump has warned Pyongyang that it faces “fire and fury”, and that Washington’s weapons are “locked and loaded”.
Trump spoke by telephone to Japan’s Prime Minister Shinzo Abe to discuss the need to “maximize pressure on North Korea” in the face of the “growing threat” it presented, according to a White House readout of the call, without specifying when it took place.
The North has repeatedly claimed that it has a thermonuclear weapon, which can be far more powerful than other nuclear devices.
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