The U.S. Air Force moved a WC-135 Constant Phoenix reconnaissance jet from the U.S. mainland to the Kadena Air Base in Okinawa, in September in preparation for another nuclear test by North Korea, the Sankei Shimbun reported Tuesday.
The WC-135, a modified aircraft, is able to detect nuclear explosions from the air by collecting samples from the atmosphere. It was stationed in Okinawa about a month before North Korea carried out its second nuclear test in May 2009. Apparently the U.S. believes that another nuclear test is imminent after unusual movements were detected at the North's test site.
Japan's Defense Ministry has also been gathering information with EP3 and YS11E electronic intelligence aircrafts, according to the daily. A Japanese government official said North Korea's preparations for a nuclear test "seem to have taken place for over half a year now, so after spending such a long time building a new tunnel, it seems unlikely they won't act."
On Nov. 17, the Sankei cited analysis of satellite pictures from British defense information firm IHS Jane's that North Korea is building a new tunnel in Punggye-ri , North Hamgyong Province, where it carried out the last test.