N. Korea preparing to conduct 5th nuclear test: S. Korea

"We are in an unpredictable situation as to what abrupt provocative action North Korea may take to avoid isolation and tighten grip on power," Park said at a meeting with senior secretaries, according to a statement posted on the presidential office website.
In a related development, the South Korean Defense Ministry's spokesman also said Monday that North Korea remains ready to conduct a fifth nuclear test any time, prompting the South Korean military to keep a close watch on the North's related activities, Kyodo reports.
"North Korea is now in a state that it can carry out its fifth nuclear test any time," Moon Sang Gyun told reporters, declining to provide further details on unusual activities at the Punggye-ri test site in the northeast of North Korea.
"We are tracking various activities and there is a likelihood" of a nuclear test, he added.
His remarks followed a report by Yonhap News Agency on Sunday, citing a South Korean government source, that activity at Punggye-ri has seen a sharp increase this month in terms of the "frequency of vehicle, workforce and equipment movements."
North Korea conducted its fourth nuclear test in January, when it claimed it had successfully detonated a hydrogen bomb -- a claim which was quickly challenged by analysts abroad.
That test, along with the launch of a satellite-carrying rocket using banned ballistic missile technology in February, led to the U.N. Security Council imposing fresh sanctions on Pyongyang.
North Korea has recently launched a series of missiles and projectiles, the latest being the failed launch last Friday of what is believed to be a Musudan medium-range ballistic missile.