North Korea could be preparing for another atomic test as President Obama prepares to visit South Korea on Friday, a Seoul defense ministry spokesman said Tuesday.
Spokesman Kim Min-seok said heightened activity has been detected at North Korea's underground nuclear test site at Punggye-ri.
"A lot of activity is currently being seen, so our forces are keeping in mind the possibility that North Korea may suddenly conduct a nuclear test in a short period of time, or as in previous cases, deceive us with what appears to be a nuclear test," Kim said at a press briefing.
Pyongyang threatened last month to conduct a "new form" of test. North Korea conducted tests in 2006 and 2009 using plutonium, but Western scientists could not determine if a 2013 test involved plutonium or uranium.
North Korea also has warned that it is preparing something "unimaginable" for its enemies and "something big" before April 30, Kim said.
White House officials said the situation demonstrates the North Korean leader Kim Jong-unls lack of its willingness for meaningful talks, South Korea's Yonhap News Agency reported.
"Given the recent North Korean statements threatening new type of nuclear tests, new type of missile tests, it's clear that North Korea is not signaling any interest in what we would consider to be credible and authentic negotiations," Evan Medeiros, Obama's key aide on Asia policy, said at a Foreign Press Center briefing. "In that context, you know, we're looking for some sign they're actually committed to denuclearization."
South Korea's foreign ministry said it is pressing international diplomatic efforts to halt additional tests, the news agency reported.
"The government's assessment is that North Korea is ready to conduct an additional nuclear test at any time upon a political decision," spokesman Cho Tai-young said. "The foreign ministry is frequently sharing related information with other ministries and keeping a close watch on North Korea's movements under close cooperation with the U.S. and other countries," he said.
The ministry is also making efforts to help the international community form a unified voice to warn the North against military provocations, he also noted.