Once upon a time, when I was a young man, Israel had several good reasons to maintain 'ambiguity.' The BIG one was that the USA was pushing the NPT and aiding Israel in violation of it. This is no longer valid. The other was that BEFORE the Yom Kippur War there was no desire in Israel to encourage a nuclear arms race in the Mideast. During the Yom Kippur War Israel delivered via the USA and it's actions at certain facilities the message to the world that it HAD a nuclear deterrent and it would use it if the existence of Israel was at risk. BOTH the USA and the Soviet Union, having satellite imaging of Israeli facilities used that evidence to PROVE to all combatants what would happen if Syrian tanks swarmed down from the Golan or Egypt pushed on towards Israel. From the fall of 1973 there was NO reality to AMBIGUITY. The proverbial cat was out of the bag. Olmert left no 'ambiguity' when he opened his mouth and anyone who pretends to 'ambiguity' now is clearly a fool. Times change. Only idiots don't.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: Obama 'strongly' opposes singling out of Israel at nuclear conference