Hi French Anonymous. Concerning your January 15, 2023 comment:
We of the RO-NW-WG thank you for detailing the special nature of the French-Israeli nuclear and conventional weapons relationship in the 1950s to 1962. I also suspect that many from the Jewish diaspora who had been working in France’s civil and military nuclear industry has shifted to Israel by 1962.
US intelligence was aware of all of this French help from many sources (French, Israeli, Jewish diaspora, human and technical) as early as the late 1940s. This is even though the official fiction still exists that US inspectors were "fooled" in the 1960s by hastily constructed brick walls in odd places within what the US knew to be Israel's “Dimona”-Negev nuclear weapons, HEU and Pu "factory" https://en.wikipedia.org/wiki/Shimon_Peres_Negev_Nuclear_Research_Center#Inspections
I won’t even go into US foreknowledge of India’s 1998 test program https://en.wikipedia.org/wiki/Pokhran-IIexcept to say the US was quite happy that India was developing weapons to almost match those of the mutual Indo-US enemy, ie. China.
As you say the US was too distracted by Vietnam in the 1960s to enforce any Israeli non-proliferation. Also with the Soviets sponsoring the “frontline Arab states” (eg. Egypt and Syria) against Israel, Israel’s enemies were generally America’s enemies (still are).
The NPT from the late 1960s https://en.wikipedia.org/wiki/Treaty_on_the_Non-Proliferation_of_Nuclear_Weapons#Israelchanged little of what the (US, UK, Western European and Soviet) intelligence world already new since the 1950s about Israel’s nascent nuclear weapons program. That program included French supplied aircraft (Mystère IV nuclear fighter bombers protected by Mirage IIIs) and Jericho I SRBMs onwards.
Yes Israel’s nuclear ambiguity permitted plausible denial of what every major intelligence agency (and their governments) knew about Israel’s nuclear weapons program.
Nuclear ambiguity permitting Western plausible deniability beats Australia's MAPW, the CND and NPT (that the little nuclear have nots mistakenly trust) any day.