A new report out of the Institute for Science and International Security (ISIS) has estimated the size of Israel’s nuclear weapons arsenal at 115 warheads, and notes that the nation is believed to have some 660kg of plutonium.

The report also says Israel has nuclear-capable cruise missiles and that, despite 1990s pledges to the US not to acquire “dual-use materials” from abroad, Israel continues to occasionally buy advanced equipment for its nuclear weapons program from abroad.

Israel is one of nine states that currently possess nuclear weapons in some form. They are the only one of these nations that does not publicly comment on the existence of its arsenal, and they have no safeguards agreement with the International Atomic Energy Agency (IAEA).

Israel’s arsenal has caused considerable problems for efforts to establish a “nuclear-free zone” in the Middle East, with the Obama Administration at one point voting in favor of a nuclear-free proposal for the region then immediately condemning the proposal, after realizing Israel is the only nation in the region with such weapons.

Efforts to hold any NPT meetings on the nuclear-free zone have similarly stalled, with Israel refusing to take part, and accusing them of “unfairly” singling them out, and demanding the NPT shift the focus to Iran, who has a civilian nuclear program, but no weapons.