Correction: An earlier version of this editorial incorrectly identified Trita Parsi as being with the Iranian-American National Council. Mr. Parsi is with the National Iranian American Council. The following version has been updated.

THOUGH FEW details of Iran’s new offer on its nuclear program have been released, two broad points were clear following this week’s negotiations in Geneva. One is encouraging: The Iranian government is more serious than it has been in years about negotiating a deal with the United States and its five partners. The other is ominous: Tehran is still insisting that it will never give up its capability to enrich uranium, which is the key to nuclear weapons production.

The detailed proposal set out by Foreign Minister Mohammad Javad Zarif was a stark change from previous rounds of negotiations , which featured filibustering by Iranian negotiators who offered only vague ideas. Mr. Zarif made clear that Iran is eager to come to an agreement that would lift the sanctions crippling its economy. He reportedly talked about finalizing an accord within three to six months.

Several reports, including one by Iran’s state news agency, suggested that the plan includes limits on the degree to which uranium would be enriched and on the number of centrifuges, as well as acceptance of a more aggressive U.N. inspection regime. As Trita Parsi of the National Iranian American Council pointed out, the proposal may resemble that offered by Mr. Zarif and Iranian President Hassan Rouhani when they last represented Iran in nuclear talks, in 2005. The scheme they presented then would have restricted Iran to 3,000 centrifuges; it now has 19,000 installed.

That 2005 plan was rejected by the Bush administration and the European Union because it would have allowed Iran to continue enrichment, which remains a central feature of the new proposal. Mr. Zarif is saying that Iran’s “right” to enrich uranium must be recognized, and it appears Tehran may be unwilling to take even the interim, confidence-building steps proposed by the United States unless this principle is conceded.

This position is troubling. No “right” to enrich uranium exists in the Non-Proliferation Treaty. Nor is enrichment needed for a nuclear power program: Many countries using nuclear power do not enrich their own uranium. On the other hand, as Mr. Rouhani himself said in a 2005 speech, a “country that possesses this capability is able to produce nuclear weapons.” Iran’s insistence on enrichment appears meant to preserve a capability for nuclear breakout after sanctions are lifted.

The Obama administration has been hinting that it could accept some Iranian enrichment, provided it was under strict controls. But any such deal would pose political challenges. Israel and France remain opposed to any Iranian enrichment, as do many members of Congress. Six Democratic and four Republican senators recently sent President Obama a letter rejecting Iran’s enrichment demands and saying that Iran should suspend all enrichment now in order to avoid further congressionally mandated sanctions.

We believe it is worth exploring a settlement that permits a token amount of enrichment while locking down the program to minimize the chance of an undetected breakout. Certainly this would be preferable to military action. But such a deal would require far greater concessions than the regime appears to be contemplating. As Russia’s deputy foreign minister put it in Geneva, the sides remain “kilometers apart.” And since Iran has yet to slow its enrichment, time is running out.