Some ironies:
Iran is a signatory state of the Nuclear Non-Proliferation Treaty and Israel is not.
To view that Iran wants negotiating leverage is to concede that they are lieing about the peaceful purpose of their program or assumes their intent to build weapons.
The three states—India, Israel, and Pakistan— that have never signed the treaty argue that the NPT creates a club of “nuclear haves” and a larger group of “nuclear have-nots” by restricting the legal possession of nuclear weapons to those states that tested them before 1967, but the treaty never explains on what ethical grounds such a distinction is valid.
North Korea initially signed, but withdrew.
The intent of the NPT, with all its faults and problems, is to create a nuclear weapon free world (disarm those that have them and any new nuclear use for peaceful purposes only).
More countries have ratified the NPT than any other arms limitation and disarmament agreement, a testament to the Treaty’s significance.