It is well-known that for a long time, Israel's public position about whether it had a nuclear arsenal was the very ambiguous statement that "Israel will not be the first area state to introduce nuclear weapons into the Middle East."
I found a State Department memo from 1969 that shows an attempt to pin down exactly what that means. .Here are some excerpts:
No one can blame the State Department from trying to parse the Israelis' words, wondering if that means that the weapons might be manufactured but not tested, or perhaps manufactured except for the very final screw being attached.
This is relevant today now that a new NIE (or similar intelligence assessment) has leaked that Iran is moving quickly to build nuclear weapons. Anti-Israel activists and Iran supporters have been using the 2007 NIE and other estimates as a talisman to deflect charges that Iran even has a nuclear weapons program, even as everyone could see for years that the Iranians were doing everything consistent with such a program short of actually announcing it - from enrichment beyond what is necessary for nuclear power to building nuclear-capable ballistic missiles to building huge underground nuclear facilities to hiding evidence of testing facilities.
The US skepticism of Israel's announcements in the 1960s was well-founded, and Israel's refusal to clarify was equally understandable. At the time, though, no one seriously believed that Israel did not have the ability to deploy a nuclear bomb in minutes if it felt it was necessary.
But for people who want to believe the Iranian denials, they have no such skepticism.