In a well-planned game of usual brinkmanship, North Korea is sending a political message that a fresh nuclear test will be conducted soon, displaying heightened activity at its test site, according to 38 North, the website of a US institute.
Satellite imagery showed a heightened level of activity with about 70-100 people standing in formation or watching in the courtyard of the Main Administrative Area at the Punggye-ri test site, 38 North said.
"Such a gathering hasn't been seen since January 4, 2013, which was followed by a nuclear test on February 12," it said, adding North Korea knows when satellites are passing overhead and typically try to avoid activities during that time.
The fact that such formations can be seen suggests that Pyongyang is sending a political message that the sixth nuclear test will be conducted soon, 38 North said. "Alternatively, it may be engaged in a well-planned game of brinkmanship."
Roh Jae-cheon, a spokesman for the South's joint chiefs of staff, said North Korea is likely to carry out a different type of nuclear test. North Korea watchers talk about a "Pakistan-type" test of blasting several bombs simultaneously, including a "boosted fission" bomb for the development of a hydrogen bomb.
In an earlier article, 38 North said Pyongyang was excavating a tunnel supporting its strongest ever detonation. In its previous test, Pyongyang claimed to have conducted a successful nuclear warhead explosion test aimed at acquiring technology for the production of diversified and miniaturized nuclear warheads to be carried by strategic missiles. Experts said it was the strongest-ever detonation that caused an artificial earthquake of magnitude 5.
North Korea's nuclear and long-range rocket tests triggered tough UN sanctions but leader Kim Jong-un has vowed to step up the development of atomic bombs and rockets capable of carrying nuclear warheads.
Lim Chang-won = email@example.com