How to play nuclear-armed poker

AMERICA, which has more deployed nuclear weapons than any other country, is open about precisely how many warheads it has in what state of readiness. Russia is a little less so, though it does share information with America. States with fewer nukes prefer not to give many details of what they are holding. China, which is the only one of the five legally recognised nuclear-armed states to be expanding its arsenal, according to the latest report from the Stockholm International Peace Research Institute, prefers this strategy. Iran, which is not yet a nuclear state, seems to follow a different strategy. Analysts think that it may have so many centrifuges spinning that it could enrich enough uranium for a bomb quite quickly—within a couple of months. But it may not go as far as to build a bomb, for risk of provoking both further sanctions and arms race in the region. Iran may thus invent a third category: states with all the kit to build a nuclear bomb that are not technically nuclear-armed states.