North Korea has already completed the development of plutonium-based nuclear weapons with the help of Pakistan, according to Japan's Chief Cabinet Secretary Hiroyuki Hosoda. This is the first time a senior Japanese official has confirmed North Korea's claim to have manufactured nuclear weapons. Pyongyang has not finished developing uranium-based nuclear weapons, but has completed, in cooperation with Pakistan, the development of a plutonium bomb similar to the one dropped by the United States on Nagasaki at the end of World War II, Hosoda said. Pakistani nuclear scientist Abdul Qadeer Khan publicly confessed in February to leaking nuclear secrets to Iran, Libya and North Korea.