SEOUL , April 22 (UPI) -- Increased activity at North Korea’s underground nuclear tests site has been detected, a South Korean government spokesman said.
Last month North Korea threatened a “new form” of test, which some experts say could involve a plutonium-based nuclear test, instead of use of a uranium-based device as in tests done in 2006, 2009 and 2013. It has recently claimed it is preparing something “unimaginable” for its enemies and “something big” to be demonstrated before Apr. 30, South Korean spokesman Kim Min-seok said.