Israel, according to published reports by many defense industry analysts, has the fifth largest nuclear arsenal in the world, but has refused to sign the Non-Proliferation Treaty or even formally admit to possession of such technology, even though it is widely-known that the Dimona Reactor in the Negev Desert has been on-line since the 60s. Pakistan and India, sharing a border and contempt for each other, have also refused to be signatories of the treaty. North Korea was once a party to non proliferation, but has since withdrawn and threatens to develop and launch a thermonuclear device. There are also reportedly weapons missing from former Soviet satellite nations.