For years the United States has pressed other countries to support and enforce U.N. Security Council resolutions that demand Iran stop all of its enrichment activities and enter negotiations. On Sunday morning in Geneva, U.S. negotiators signed an interim agreement that would tolerate “a mutually-agreed long-term comprehensive solution” for Iran, according to the text of the deal.

The agreement signed in Geneva says Iran and six world powers will negotiate over the next six months “would involve a mutually defined enrichment program with practical limits and transparency measures to ensure the peaceful nature of the program.”

To be sure, the idea that Iran would be able to enrich uranium after a final status deal has been floated in negotiations for the last two years. But the offer represents a significant softening of earlier demands from the United States and even the Obama administration. During his first term, Obama offered Iran a deal that would have required Iran to import enriched nuclear fuel, but not allow Iran to make that fuel in facilities its government controlled.

The agreement in Geneva is meant to build trust between Iran, China, France, Germany, Russia, the United States and the United Kingdom as their diplomats hammer out a final agreement to end Iran’s quest for a nuclear weapon. For now, the world is offering Iran modest sanctions relief in exchange for more transparency regarding its program and an agreement to cap its stockpile of enriched uranium during the talks.

Already this language has drawn fire from top Republicans. In a statement Sunday morning, House Majority Leader Eric Cantor (R-VA) said, “The text of the interim agreement with Iran explicitly and dangerously recognizes that Iran will be allowed to enrich uranium when it describes a 'mutually defined enrichment program' in a final, comprehensive deal. It is clear why the Iranians are claiming this deal recognizes their right to enrich.”

On a phone call with reporters Saturday evening, senior administration officials said the deal did not recognize Iran’s right to enrichment and that limitations on Iran’s enrichment would be negotiated over the next six months.

David Albright, a former weapons inspector and the president of the Institute for Science and International Security, said the document does not explicitly acknowledge that Iran has a right to enrich uranium, the process for creating the fuel needed for a peaceful nuclear reactor and also a nuclear weapon. But he also said he was troubled that the language on enrichment was so vague.

“I would have hoped some of the parameters were clarified in the initial deal,” he said. “How many centrifuges are we talking about? Is it 18,000 or 3,000? How long will these limitations last, five years or twenty years?”

Since 2005, when Iran began spinning centrifuges at Natanz, a facility first disclosed to the public by an Iranian opposition group known as the People’s Mujahedin, the U.S. has called on Iran to stop enrichment altogether. Under the Bush administration, the U.S. declined to even negotiate at first with Iran so long as it continued to enrich uranium.

Over time that condition for the United States melted away. But even President Obama has said that he does not recognize Iran’s right to enrich uranium under the Nuclear Nonproliferation Treaty.

Robert Zarate, the policy director for the Foreign Policy Initiative, a think tank that has supported more sanctions on Iran, said the deal signed in Geneva was dangerous. "We're another step closer to a nuclear-1914 scenario in the Middle East or elsewhere,” Zarate said. “If we cannot say 'no' to Iran -- a country, by the way, that's repeatedly violated the Nuclear Nonproliferation Treaty, international nuclear inspections and U.N. Security Council resolutions -- then good luck getting countries who haven't broken any rules, including some of America's allies and partners, to refrain from getting enrichment and reprocessing or, perhaps eventually, nuclear weapons."