though often controversial - nuclear nations include North Korea - which announced its withdrawal from the NPT in January 2003 - where experts believe there is enough plutonium for six to eight bombs; India, which is likely to have manufactured weapons-grade plutonium for at least 100 warheads and Pakistan, which is believed to have stockpiled about 580-800 kilograms (1,279-1,764 pounds) of highly enriched uranium, sufficient to build 30 to 50 fission bombs. Neither India nor Pakistan are signatories to the NPT.
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