North Korea has increased the activity at its Punggye-ri nuclear test site ahead of President Barack Obama’s visit to South Korea.
South Korean military was “currently detecting a lot of activity in and around the Punggye-ri nuclear test site”, a South Korean defense ministry spokesman said.
North Korea could be planning to hold a “surprise nuclear test or just pretend to stage a nuclear test”, he said.
The communist country has carried out three nuclear tests in the past.
South Korea’s foreign minister warned of the dangers of another.
“If North Korea goes ahead with another nuclear test as it has publicly warned, it will be a game changer,” Yun Byung-se said.
North Korea’s most recent test was in February 2013 – an incident that triggered several months of severe tension on the Korean peninsula.
It also carried out tests in 2006 and 2009.
All of the tests – which were signposted well in advance – resulted in the imposition of UN sanctions on Pyongyang.
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