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Explosive yield estimate of N. Korea nuclear bomb test may be upgraded

The initially estimated explosive yield of the nuclear bomb
recently tested by North Korea, calculated based on the size of the
subsequent earthquake, is likely to be upgraded, Japanese Defense
Minister Itsunori Onodera said Tuesday.

The destructive potential of the detonated bomb may be "much
stronger than" the Japanese government previously evaluated, Onodera
said at a press conference.

Following Pyongyang's sixth nuclear test on Sunday, data from
the Preparatory Commission for the Comprehensive Nuclear-Test-Ban
Treaty Organization estimated the magnitude of the blast at 5.8,
suggesting the bomb had a yield of around 70 kilotons.

The magnitude of the jolt from the nuclear test is expected to
be upgraded to as high as 6.0, Onodera said. After the magnitude is
determined, the Defense Ministry will analyze the explosion of the
bomb again, which North Korea claims was a hydrogen bomb.

"We cannot rule out the possibility that it was a hydrogen bomb,
but it may have been a boosted atomic bomb. Analysis is necessary,"
he added.

Meanwhile, a so-called nuclear sniffer plane, the Air Force
WC-135 Constant Phoenix, arrived at Kadena Air Base in Okinawa,
southern Japan, about 7:40 a.m. Tuesday, a government source said.

The plane is set to detect radioactive materials and gather
other data to assess the impact of Sunday's nuclear test, the source
said. (Sept. 5)

Japanese Defense Minister Itsunori Onodera speaks to reporters at his ministry in Tokyo on Sept. 5, 2017. Onodera said North Korea's latest nuclear test may have had an explosive yield of about 120 kilotons, much higher than the Japanese government's initial estimate based on seismic data. (Kyodo)