The Iranians are demanding that they be allowed to keep the advanced nuclear-fuel production equipment they installed after Mr. Trump abandoned the pact, and integration with the world financial system beyond what they achieved under the 2015 agreement.
The Biden administration, for its part, says that restoring the old deal is just a steppingstone. It must be followed immediately by an agreement on limiting missiles and support of terrorism — and making it impossible for Iran to produce enough fuel for a bomb for decades. The Iranians say no way.
Now, as negotiators engage again in Vienna, where a new round of talks began on Friday, the Biden administration finds itself at a crucial decision point. Restoring the 2015 accord, with all its flaws, seems doable, interviews with European, Iranian and American officials suggest. But getting what Secretary of State Antony J. Blinken has called a “longer and stronger” accord — one that stops Iran from amassing nuclear material for generations, halts its missile tests and ends support of terrorist groups — looks as far away as ever.