Iran and world powers agreed to extend negotiations over Tehran’s nuclear program after a comprehensive deal proved elusive as the latest deadline approached. In a new Q&A, George Perkovich details where the talks stand and analyzes what lies ahead. Perkovich says Washington and its allies should strategically continue patient diplomacy unless Iran resumes provocative nuclear activities.

Why were the sides unable to reach a comprehensive accord by the November 24 deadline? What are the major sticking points?

Iran, on one side, and the United States, France, the United Kingdom, Germany, Russia, and China, on the other side, approach the negotiations in profoundly different ways.

The P5+1 has long seen the issue as a compliance problem: Iran demonstrably broke rules requiring transparency in its nuclear program and conducted activities that suggest that its nuclear program has not been exclusively peaceful, as required under the Nuclear Non-Proliferation Treaty. Thus, Iran must take steps to build international confidence that (notwithstanding its violations of rules) its nuclear program will be exclusively peaceful in the future.

Iran has argued that the rules have been unfairly applied and that the situation can be resolved only through bargaining that places Tehran on equal footing, not as an object of compliance. Having suffered through major international sanctions, isolation, and covert operations against its scientists and facilities, leaders insist Iran will not give up the capabilities it has developed, including, most famously, enrichment of uranium.

Iran has won considerable gains in this process, insofar as the P5+1 is now prepared to accept some ongoing enrichment and other nuclear activities that the world powers previously demanded Tehran to cease.

The most challenging difference is over how much enrichment capability Iran will have to disable, and how much it will be allowed to retain. Relatedly, the parties disagree over the duration of the limitations on Iran’s activities. The details remain unknown publicly, but it appears that the P5+1 insists that Iran not operate some 10,000 centrifuges it now has assembled in reserve, and reduce by some thousands the 9,000 centrifuges it has been operating. It is not clear whether Iran has agreed to disable any of the operating centrifuges; Iranian negotiators certainly have not been willing to reduce these numbers by anything like the amount demanded by the P5+1.

Another major gap between the two positions concerns the process of sanctions relief that Iran would gain through a deal. Iran wants international sanctions to be removed completely and quickly. The United States and others insist that sanctions can be suspended at first rather than removed, and that this be done in phases corresponding to Iran’s implementation of its side of any bargain. The most “biting” sanctions would remain until Iran completed the implementation of an agreement. The choreography of this process has still not been agreed.

Similarly, the duration of an overall agreement and its various phases remains unsettled. There are probably other disagreements on fundamentals. And if and when those can be worked out, painstaking negotiations then have to be completed on the technical details of implementation.

Obviously, all of this is extremely complicated. More important, however, is the basic issue that what Iranian leaders think should be sufficient actions on their part are still inadequate to the P5+1 and other stakeholders, and what the United States and others are willing to accept is inadequate for the Supreme Leader of Iran and some of the stakeholders he seeks to satisfy.

Underneath all of this are differences in perceptions of what a reasonable, exclusively peaceful nuclear program in Iran should entail. Iran insists on retaining certain capacities that others judge to be beyond what is necessary, and therefore suggestive of a desire to perhaps produce nuclear weapons in the future.

What are the details of the seven-month extension?

Few details are public. The basic idea seems to be to seek agreement on the fundamentals of a deal by March, allowing for the completion of plans and procedures for its technical implementation between March and June.

Beyond that, the logic is that Iran should continue to abide by the restraints on its nuclear activities, especially enrichment, as it has done since the Joint Plan of Action went into force in January 2014. And the United States and its partners should continue to allow Iran access to funds in various sanctioned accounts that it has been able to tap under the temporary agreement.

In other words, all sides will continue to uphold the Joint Plan of Action, recognizing that it has been mutually beneficial.

How is the U.S. Congress likely to react? Will new sanctions be added?

One can predict that some in Congress—Democrats as well as Republicans—will press for new sanctions on Iran. They will argue that enough time has been allowed to ascertain whether a comprehensive agreement can be reached, and that Iran is simply unwilling to take the steps necessary for such a deal.

Some will say that additional sanctions will change Iran’s incentives sufficiently to motivate new concessions; others will say that Iran will never change, so the point of new sanctions would simply be to punish it.

But there is a risk, which other members of Congress will articulate. If the United States unilaterally adds new sanctions, Iran will react by resuming threatening nuclear activities that it has ceased under the Joint Plan of Action. New sanctions may hurt Iran, but resumed nuclear activities may threaten the international community in return.

Another concern is that if Congress enacts new sanctions unilaterally, and before Iran resumes provocative nuclear activities, other states will blame the United States for increasing international danger. Then, international support for sanctions could falter and states such as Russia, China, Turkey, India, and others could resume trade and investment with Iran, blaming the United States. Were this to happen, the concern is that Iran will be able to loosen the pressures it has been under and the international community will be worse off than it has been in the past year.

Opponents of new sanctions can make a compelling argument that it is strategically unwise to allow the United States to be seen as the actor provoking a breakdown in the current situation, and it would be much wiser to withhold implementing new sanctions until Iran makes the first new provocative move. If Iran does make such a move, it would take Congress hours or days to vote overwhelmingly for new sanctions in response. If Iran maintains self-restraint, then this should be welcomed at least while negotiations are ongoing.

In other words, as my colleague Karim Sadjadpour has put it, a strategically wise approach is to lock in Iranian restraint, deter an Iranian break out from the Joint Plan of Action, and incentivize Iran to take further steps to reassure others that it is not seeking nuclear weapons. To this end, Congress could authorize new sanctions that would be implemented if and when Iran breaks the terms of the Joint Plan of Action, and authorize additional marginal relief of sanctions if Iran takes further steps to build confidence that it will not seek nuclear weapons.

How will hardliners in Iran respond and will this have implications on the negotiations?

Iranians have an exceedingly difficult time predicting their politics, so I am very cautious about undertaking such predictions myself. It is safe to say that there are elements in Iran who profit from and welcome enmity with the United States and relative economic isolation.

They fear the loss of influence and economic advantage that could come with greater openness. They worry that a successful negotiation will be very popular in Iran and politically beneficial to President Rouhani and his team. Such people may welcome a breakdown in negotiations more than a successful completion. In this sense, Rouhani and his team may see a continuation of the process as the least-bad outcome for now.

If this is correct, then moves by the U.S. Congress to add new sanctions immediately would increase the opportunity for opponents of rapprochement and of Rouhani to take provocative steps that could scuttle diplomacy. The temptation would be all the greater if these people calculate that U.S. sanctions would motivate other states to split from the sanctions coalition that has been created over the past six years.

What are the chances that a deal can be reached by the next deadline?

This is impossible to predict with any confidence. It is difficult to see what new developments would prompt the United States and its partners to change the offers they have made to Iran. In particular, it is hard to imagine political or other changes in the regional setting that would motivate a lessening of requirements.

It seems that the variable that is subject to some change could be within Iran, depending how broader political and economic trends evolve in the next few months. Absent internal changes that make the Supreme Leader conclude that the revolutionary system he supports will be jeopardized without a deal, it is hard to see what would motivate him to amend the positions his negotiators have taken so far.

What are the risks if a deal isn’t ultimately struck?

The answer to this question depends largely on how one perceives the benefits and costs of the status quo under the Joint Plan of Action, and if the parties are be willing to maintain this modus vivendi even if the next round of negotiations fails to yield a more ambitious agreement.

Those who judge the current situation to be better than what prevailed previously, and better than it would be, for example, if Iran broke out or was attacked militarily, will conclude that continuing to manage irresolution is tolerable. Those who judge the current status quo as worse than alternatives other than a comprehensive deal on the P5+1’s terms will embrace the risk of more dramatic action.

When I look at the story of U.S.-Iran relations since 1979, and at the course of nuclear dynamics with Iran between 2005 and now, I think that the present situation, however unresolved, is an improvement. Things could be much better, but they could be much worse too. Thus, it would be wise to remain calm and strategic and to continue patient diplomacy unless and until Iran acts in provocative ways that warrant a more bellicose policy.