Nine countries in the world own nuclear warheads. The total warhead inventory includes those that have been deployed, kept in reserve or retired from the military stockpile and have not yet been dismantled.

The Brief. Nine countries are listed as having nuclear weapons, according to the Stockholm International Peace Research Institute. Russia is the number one on the list with more than 4,000 nuclear warheads, followed by the U.S. with over 3,000.

Israel is widely believed to have nuclear weapons, though it has neither acknowledged nor denied having a nuclear arsenal. After Israel launched its war against Iran vowing to take out the country's nuclear program before it had the ability to produce weapons, fresh scrutiny has fallen on the country's own arsenal.