There’s a charming naiveté to the open letter [PDF] by 47 Republican senators that condescendingly seeks to explain features of the U.S. constitutional system to Iran’s leaders that they otherwise “may not fully understand.”

The missive warns that, with respect to “your nuclear negotiations with our government ... any agreement regarding your nuclear-weapons program that is not approved by the Congress” could be revoked by the next president “with the stroke of a pen and future Congresses could modify the terms of the agreement at any time.”

Beyond the amusing inaccuracies about U.S. parliamentary order, it seems there are some features of the nuclear negotiations that the signatory senators don’t fully understand — not only on the terms of the deal, but also on who would be party to an agreement.

There are no negotiations on Iran’s “nuclear-weapons program” because the world’s intelligence agencies (including those of the U.S. and Israel) do not believe Iran is currently building nuclear weapons, nor has it made a strategic decision to use its civilian nuclear infrastructure to produce a bomb. An active Iranian nuclear-weapons program would render moot the current negotiations, because Iran would be in fundamental violation of the Nuclear Non-Proliferation Treaty (NPT).

As things stand, Tehran remains within the terms of the NPT, which allows nuclear technology for peaceful purposes, but monitors member states to prevent weaponization. Tehran and the IAEA remain in dispute over full compliance with all transparency requirements of the NPT, particularly over alleged previous research into weapons design. But Iran’s nuclear facilities remain under constant monitoring by international inspectors who certify that no nuclear material is being diverted.

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.