While it’s true that the April deal was only a framework, and that some changes should have been expected, all these concessions taken together represent a retreat by the U.S. team since the spring. “The fact sheet allowed just enough wiggle room to give the impression that nothing had been conceded in Lausanne,” Valerie Lincy, the executive director of the Wisconsin Project on Nuclear Arms Control, told me. “But when I read the agreement, it’s clear there are things that have been conceded in terms of the details on advanced centrifuges, reprocessing of plutonium and the inspections.”

The concessions involving Iran’s development of advanced centrifuges starting in year eight are particularly alarming. Blaise Misztal, the director of the national security program for the Bipartisan Policy Center, told me this constituted a “step back.” Such advanced centrifuges can enrich a greater amount of uranium more rapidly than Iran’s antiquated IR-1 model centrifuges by orders of magnitude.

David Albright, a former weapons inspector who is now president of the Institute for Science & International Security, also told me the centrifuge concession was a surprise: “It seems to open a way for Iran to expand their advanced centrifuges earlier than I expected or wanted.” He predicted that the advanced IR-6 and IR-8 centrifuges Iran would be allowed to install by year 13, “would allow Iran to lower its break-out times down to days or a few weeks.”