Former President Carter spills the beans (finally)

tells an audience in the U.K. that Israel has an arsenal of some 150 nuclear weapons.
Well that is nothing for Jimmy, I believe he ordered up a secret CIA report in 1977 or on Israel's nuclear weapon's potential. More than likely that report told him the State of Israel had already crossed the threshold with respect to deliverable nuclear warheads. That in turn prompted Carter to kibbutz Moshe Dayan on the subject after he became Begin's foreign minister...to be sure Carter received no satisfaction on the matter.
To be sure, Israel got the bomb in the 1968 thru 1972 period a time when their opponents were being heavily armed and patronized by the USSR. In turn the USSR's diplomatic and military presence in the region dictated a policy of "nuclear ambiguity" for Israel Summarized as "we might have em' but if we did we wouldn't talk about em'...so let us not discuss it shall we?"
It seems strange to modern audiences but quite clearly the Labor and Likud Governments of 1970's all feared that if Israel came clean about the bomb the Arabs would repudiate their commitments under the Non Proliferation Agreement and seek protection under the Soviet Nuclear "Umbrella".
Humble Elias wrote a lot about this topic back in graduate school y'unnerstan'.
Personally I think ambiguity has "tarried too long for the good it hath done", everyone knows Israel has the bomb, they keep the lid on because of bureaucratic inertia and fears that if they come clean the US Non Proliferation Act could be applied against them.
As if that law wouldn't be modified toot-sweet by congress to exempt Israel if it came down to it....
Of course, Israel could "come clean" and sign the Non Proliferation Treaty as a "nuclear weapons state", the USA and the USSR did so in 1968 there is reason why Israel can't do the same. It isn't a perfect solution but it is a first step in a region with few arms control safeguards.
It also might put some diplomatic pressure on Iran whose veracity on this subject ought to treated with reasonable skepticism.