Both Secretary of State John Kerry and Iranian president Hassan Rouhani are saying that a deal on Iran's nuclear deal is within reach, leading to speculation that an agreement may be imminent.

The United States and Iran reported significant progress Saturday toward a nuclear agreement, with the Iranian president declaring a deal within reach. America's top diplomat was more reserved, leaving open whether world powers and Tehran would meet a March 31 deadline.

Speaking after a week of nuclear negotiations in Switzerland, U.S. Secretary of State John Kerry challenged Iran to make "fundamental decisions" that prove to the world it has no interest in atomic weapons. Amid conflicting statement by officials about how close the sides were, Kerry said, "We have an opportunity to try to get this right."

The talks "have made substantial progress," Kerry told reporters, "though important gaps remain." Talks with Iran resume next week.

In Tehran, Iranian President Hassan Rouhani was more optimistic. "Achieving a deal is possible," he said. "There is nothing that can't be resolved."

Other negotiators offered both positive and negative assessments. Top Russian negotiator Sergey Ryabkov and Iran's atomic energy chief Ali Akbar Salehi said in recent days that technical work was nearly done. But French officials said the opposite, declaring the sides far from any agreement.

France is sounding the alarm about the potential deal:

French diplomats have been publicly pressing the U.S. and other world powers not to give ground on key elements—particularly the speed of lifting U.N. sanctions and the pledge to constrain Iran’s nuclear research work—ahead of the March 31 target.

Paris also appears to be operating on a different diplomatic clock than Washington, arguing that the date is an “artificial” deadline and that global powers should be willing to wait Tehran out for a better deal if necessary.

Obama administration officials have said that expected moves by the U.S. Congress to put new sanctions on Iran as soon as April limit their ability to extend the diplomacy.

But French officials took exception.

“Making the end of March an absolute deadline is counterproductive and dangerous,” France’s ambassador to the U.S., Gérard Araud, said via Twitter after the latest round of negotiations in Switzerland concluded Friday.

“No agreement without concrete decisions on issues beyond the enrichment capability question,” he said a day earlier, specifically mentioning the need for extensive monitoring and clarity on Iran’s past research work. Western officials believe they included the pursuit of nuclear-weapon capabilities.

There's one of two explanations for the seemingly rapid progress over the last few hours: either Iran has substantially altered its position and is making concessions, or the U.S. and the West are caving in to Iranian demands.

Which do you think is more likely?

The French government won't blow up the talks by claiming a Western surrender.  They don't want to go to war over Iran's nuclear program any more than Obama does.  Nor do they want to be blamed if the talks collapse.  All they can do is point out the obvious and keep their mouths shut otherwise.

The administration and Kerry have been moving the goal posts for months.  The only progress has come when the West has acceded to the Iranian position.  We have gone from a ten-year deal, with sanctions being gradually lifted over that time, to a deal of unspecified length with the major sanctions lifted in weeks.  When you consider that the Iranians will interpret this deal any way they see fit and the administration won't dare call them out for violating it, Iran is sitting pretty at the moment.

Yes, but at least Obama will make "history" by enabling the Iranian nuclear bomb program.