North Korean Supreme Leader Kim Jong-un. Photo: Flickr.

North Korea said Friday it conducted a “higher level” nuclear warhead test explosion, which it trumpeted as finally allowing it to build “at will” an array of stronger, smaller and lighter nuclear weapons. It is Pyongyang’s fifth atomic test and the second in eight months.

South Korea’s president called the detonation, which Seoul estimated had produced the North’s biggest-ever explosive yield, an act of “fanatic recklessness.”

Read full story at CBS News.