According to Hans M. Kristensen, the director of the Nuclear Information Project at the Federation of American Scientists, underground vaults at Incirlik hold about fifty B-61 hydrogen bombs—more than twenty-five per cent of the nuclear weapons in the NATO stockpile. The nuclear yield of the B-61 can be adjusted to suit a particular mission. The bomb that destroyed Hiroshima had an explosive force equivalent to about fifteen kilotons of TNT. In comparison, the “dial-a-yield” of the B-61 bombs at Incirlik can be adjusted from 0.3 kilotons to as many as a hundred and seventy kilotons.