The NATO Interpretation of NPT Withdrawal
The key document on the US interpretation of Articles I and II is entitled Questions on the Draft Non-Proliferation Treaty asked by US Allies together with Answers given by the United States. (See Annex 2.) The Questions and Answers were enclosed with a letter from Secretary of State, Dean Rusk, to President Johnson. The letter and the Questions and Answers were then transmitted to the Senate on 9 July 1968, along with other relevant documents, for consideration during the Senate ratification hearings on the NPT. This interpretation was thereby made public on 9 July 1968, eight days after the NPT signing ceremony at which the first 56 nations had signed the Treaty.
They also point out:
The US is the only country which has explicitly stated that once a general war has begun, it would no longer feel bound by the NPT. It has thus created a loophole by which it could withdraw from the Treaty without the three month notice period required by NPT article X. In addition, the US approach implicitly creates a loophole for NNWS members of NATO to withdraw from their treaty obligations and receive US nuclear weapons in the event of war.
The Questions and Answers themselves can be found at PENN; here is the relevant passage from what was transmitted to the Senate:
3. Q. Does the draft treaty prohibit arrangements for the deployment of nuclear weapons owned and controlled by the United States within the territory of non-nuclear NATO members?
A. It does not deal with arrangements for deployment of nuclear weapons within allied territory as these do not involve any transfer of nuclear weapons or control over them unless and until a decision were made to go to war, at which time the treaty would no longer be controlling.
I suspect that there is some diligent diplomat in the Iranian Foreign Ministry who has all this laid out for presentation to the UN Security Council within a few hours of any military action. I wouldn't count on a 3-month grace period before enrichment starts.
Hoist, petard, etc.