By 1969, U.S. Defense Secretary Melvin Laird believed that Israel might have a nuclear weapon that year.[80][81] Later that year, U.S. President Richard Nixon in a meeting with Israeli prime minister Golda Meir pressed Israel to "make no visible introduction of nuclear weapons or undertake a nuclear test program", so maintaining a policy of nuclear ambiguity.[82] Before the Yom Kippur War, Peres nonetheless wanted Israel to publicly demonstrate its nuclear capability to discourage an Arab attack, and fear of Israeli nuclear weapons may have discouraged Arab military strategy during the war from being as aggressive as it could have been.[1]
The CIA believed that Israel's first bombs may have been made with highly enriched uranium stolen in the mid-1960s from the U.S. Navy nuclear fuel plant operated by the Nuclear Materials and Equipment Corporation, where sloppy material accounting would have masked the theft.[83][84]
By 1974, the U.S. intelligence community believed Israel had stockpiled a small number of fission weapons,[85] and by 1979 were perhaps in a position to test a more advanced small tactical nuclear weapon or thermonuclear weapon trigger design.[86]
The CIA believed that the number of Israeli nuclear weapons stayed from 10 to 20 from 1974 until the early 1980s.[21] Vanunu's information in October 1986 said that based on a reactor operating at 150 megawatts and a production of 40 kg of plutonium per year, Israel had 100 to 200 nuclear devices. Vanunu revealed that between 1980 and 1986 Israel attained the ability to build thermonuclear weapons.[34] By the mid 2000s estimates of Israel's arsenal ranged from 75 to 400 nuclear warheads.[8][21]
