The interim nuclear agreement with Iran has made the world a safer place. Iran is further away from a nuclear bomb and the United States is further away from bombing Iran. But this interim deal is not sustainable. Unless the paradigm guiding the ongoing negotiations shifts, a final deal is unlikely to be reached and the gains of the interim deal will be lost.

For the United States and Iran, the negotiations departed from the point of near complete mistrust. This contributed to an approach where both sides tried to compel the other to change its behavior by applying pressure. Both sides continue to believe that it was this pressure that caused the other to seriously negotiate. At the same time, they strongly reject that the pressure they themselves were subjected to prompted their own shift in behavior.

The gospel in Washington holds that sanctions brought the Iranians to the negotiating table. Sanctions helped cripple the Iranian economy and forced the Iranians to negotiate, the reasoning goes. Hardliners in Iran, in turn, maintain that the expansion of Iran's nuclear program compelled Washington to drop its refusal to negotiate. The centrifuges brought America to the table, the Iranian argument reads.

This excessive focus on pressure as the sole instrument to compel changes in behavior has contributed to the current deadlock in negotiations. If one believes that pressure has generated flexibility on the other side, then one will be loath to give up that leverage, otherwise one's counterpart might revert back to its previous policy.

Following this logic, Washington insists on significant concessions from the Iranian side, but in return only offers to suspend some sanctions upfront, postponing the actual lifting of sanctions to a much later date. The U.S. side fears that if the sanctions - its main leverage - are lifted earlier, Iran will no longer have any incentive to comply with the agreement. And once sanctions are lifted, reimposing them will be a monumental task, leaving Iran with the freedom to expand its nuclear program with impunity. Again, absent pressure, Iran will not move in the right direction, the paradigm dictates.

Similarly, Tehran has agreed to freeze some of its nuclear activities, but insists on maintaining its functioning centrifuges - the core of its leverage. Just as the U.S. and the EU want to reduce the centrifuge count to lengthen Iran's breakout capability, Tehran may calculate that a shorter breakout period will give it leverage over the international community to ensure that it follows through on the sanctions relief it has promised.

Operating in the pressure paradigm, neither side can imagine alternative drivers of behavior. The notion that a deal could change Iran's incentive structure and make it not desire actions that would violate the deal simply do not fit within this paradigm. Similarly, the Iranians do not trust that the West would see adhering to the deal as being in its interest absent Iran being on the verge of breakout.

The assumptions of this paradigm have always been questionable at best. Pressure played a far lesser role than the two sides like to maintain. In reality, the negotiations took off because the pressure path was leading to a dead end— a war neither side wanted. In addition, there was a mutual concession: both sides accepted the other's red line. Iran accepted America's red line of not building a nuclear weapon and the Obama administration accepted the Iranian red line that it would not be deprived of the capacity to enrich uranium on its own soil.

Just as the pressure paradigm did not bring about the negotiations, the last round of negotiations have made clear that it is even less likely that it will bring about a durable deal. For a solution to be reached and endure, both sides need to feel that they won something. Pressure cannot bring about that sentiment. No one can be pressured into feeling like a winner.

Durable solutions are found when both sides feel that they have gained something they do not want to lose and that they cannot obtain through other means. Their incentives are transformed. They no longer want to cheat because they are more satisfied within the agreement than outside of it. Not necessarily because of the punishment they would suffer, but because of the gains they would lose.

This does not mean that pressure is not needed. Every strategy needs various doses of pressure at various points. But any solution that is sought solely through the means of pressure suffers from an inescapable paradox.

To compel the other side to negotiate, you need pressure and leverage, it is assumed. For the other side to agree to change its behavior, however, you need to offer giving up that leverage as an incentive. But once the pressure is relieved, so is the incentive of the other side to comply with the agreement, the paradigm dictates, causing the deal to fall apart.

The paradox is caused by a flaw in the paradigm's foundational assumption: The behavior of the other side can only be changed through pressure.

There is no solution to this paradox. The paradigm needs to be discarded altogether.

Rather, any deal needs to be embedded in a web of other arrangements that changes the incentive structure of both sides. The leap of faith both sides must take to strike a deal must be balanced by measures following the deal that tie the two together and raise the cost for reverting back to the previous posture and policies.

For Iran, the prospect of shedding its pariah status and being integrated into the political and economic structures of the region and the global economy will be a profoundly potent deterrent against any impulse to restart the controversial dimensions of the nuclear program. The fear of losing this new acceptance will be more powerful than the fear of shouldering new economics sanctions.

For the U.S., the reduction of tensions following a nuclear deal and increase in discreet collaboration on regional matters such as the efforts against ISIS in Iraq, will be of tremendous value. As Ali Shamkhani, Secretary of Iran's Supreme National Security Council said last month: After a nuclear accord has been signed, Iran in the United States “can behave in a way that they do not use their energy against each other." The cost of losing Iran as a neutral, or better yet, stabilizing force in the region will be a stronger deterrent against any foul play on sanctions relief than Iran retaining a few more hundred centrifuges.

The deadline for the nuclear negotiations has now been extended twice. There cannot likely be a third extension. This leaves the negotiators with only a few more weeks and months to shift their paradigm.

Trita Parsi is the author of A Single Roll of the Dice - Obama's Diplomacy with Iran (Yale University Press, 2012). He tweets at @tparsi.