A new international report estimates that North Korea possesses up to 20 nuclear warheads.

In an annual report by the Stockholm International Peace Research Institute(SIPRI) released on Sunday, it was estimated that the North had 10 to 20 nuclear warheads, presumably built using plutonium produced through the reprocessing of spent fuel rods.

The Swedish institute said although it is unlikely Pyongyang has developed miniaturized nuclear warheads to mount on a ballistic missile that can strike the U.S. mainland, the regime is believed to be able to build a compact warhead that can be delivered by short- and medium-range missiles.

It also pointed out that the North is putting its priority on developing a nuclear-capable long-range ballistic missile that can reach the United States. 

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