Paul R. Pillar [“Misreading Iran’s intentions,” Washington Forum, Nov. 1] wrote that an unwillingness by the five permanent members of the U.N. Security Council and Germany to offer Iran substantive sanctions relief in exchange for verifiable concessions would doom efforts to clinch a nuclear deal.

An even more imminent risk to these talks is the prospect of Congress pushing new sanctions before diplomats have an opportunity to negotiate a crisis-ending deal. If Congress were to defy the Obama administration by passing sanctions now, it would signal to Iran that Congress is only after regime change and is unwilling to adapt to reasonable changes in Iran’s nuclear posture. It would undermine confidence in Tehran that President Obama can deliver on sanctions relief in the final stages of an agreement.

For the first time in years, the United States and Iran are on a path toward an agreement to guard against a nuclear-armed Iran and prevent a catastrophic war. Congress should welcome these efforts, not sabotage them.

Kate Gould, Washington

The writer is the legislative associate for Middle East policy at the Friends Committee on National Legislation.