The current negotiations are focused on strengthening verifiable safeguards against weaponization over-and-above those required by the NPT, yet the Republican-led Congress, egged on by Israeli Prime Minister Benjamin Netanyahu, is warning that those goals are insufficient, and the terms and time-frame of the deal are unacceptable.
The key element missing from the GOP Senators’ letter, however, is that the deal is not being negotiated between Iran and the United States; it is being negotiated between Iran and the P5+1 group, in which the U.S. is joined by Britain, France, Germany, Russia and China. Even if the U.S. is the key player in that group, the deal being pursued reflects an international consensus — the same consensus that has made sanctions against Iran so effective.
This was likely in the mind of Iran’s foreign minister, Javad Zarif, who dismissed the letter as “of no legal value” and a “propaganda ploy.” Zarif noted that the deal would indeed be an international agreement adopted by the U.N. Security Council, which a new administration would be obliged to uphold — and that any attempt by the White House or Congress to abrogate, unilaterally modify or impede such an agreement would be a breach of U.S. obligations.