Communist China is probably one of the greatest threats to the US and the US would be wise to modernize and re-vamp it's nuclear arsenal to keep them in check. It would also be in the United States' best interest to bring Putin and Russia into the Western fold to stabilize Europe and to develop an ally against China. There is, unfortunately, very little chance that the spread of nuclear weapons can be checked. The Iranian situation is the latest failure to prevent the rogue development of the bomb. The best means of preserving world peace remains mutually assured destruction or, in the case of the rogue cases, assured destruction.