Israel has 80 nuclear warheads and the potential to double that number, according to a new report by U.S. experts. In the Global Nuclear Weapons Inventories, recently published in the Bulletin of the Atomic Scientists, proliferation experts Hans M. Kristensen and Robert S. Norris write that Israel stopped production of nuclear warheads in 2004. But the country has enough fissile material for an additional 115 to 190 warheads, according to the report, meaning it could as much as double its arsenal. Previous estimates have been higher but the new figures agree with the 2013 Stockholm International Peace Research Institute yearbook on armament and international security. The yearbook estimated 50 of Israel's nuclear warheads were for medium-range ballistic missiles and 30 were for for bombs carried by aircraft. Although widely assumed a nuclear power, Israel has never acknowledged possessing nuclear weapons or capabilities and continues to maintain its decades-old strategic ambiguity" policy on the matter, neither confirming nor denying foreign reports on the issue. In 1986, Mordechai Vanunu, an Israeli nuclear technician, leaked the country's alleged nuclear secrets to a British newspaper, and said Israel had at least 100 nuclear weapons. Vanunu was later convicted of espionage and treason and was released from jail in 2004 after serving 17 years. Israel continued to adhere to its vagueness policy after comments made by then-Prime Minister Ehud Olmert in 2006 were interpreted by many as an inadvertent confirmation that Israel had nuclear weapons.