Paul R. Pillar is a nonresident senior fellow at Georgetown University’s Center for Security Studies and the Brookings Institution.

There are popular fundamental misconceptions about Iran’s nuclear program: that the Iranian leadership has a fixed goal of acquiring a nuclear weapon, that if left alone Iran would build such a weapon and that this presumed ambition will be thwarted only if the rest of the world imposes enough costs and barriers. These misconceptions infuse much of the U.S. discourse on Iran, as reflected in frequent, erroneous references to Iran’s “nuclear weapons program.” These mistakes encourage a posture toward Iran that makes it more, not less, likely that Tehran will decide someday to build a bomb.

Public U.S. intelligence assessments are that Iran has not made any such decision and might never do so. Iranians have been interested in the option of a nuclear weapon, and some of their nuclear activities have helped to preserve that option. Whether they ever exercise the option depends primarily on the state of their relationship with the rest of the world, particularly the United States. As they sit down for their next round of talks with Foreign Minister Mohammad Javad Zarif, the United States and its negotiating partners have an opportunity to forge a relationship with an Iran that remains a non-nuclear-weapons state — not so much because of technical barriers they might raise, but because the relationship would be one in which the Iranians would not want a nuclear weapon.

The principal purpose for which Iran might seek such a weapon is deterrence against attacks on its homeland. This is the main reason that threats of military strikes are counterproductive. It is also why the likelihood of an Iranian bomb would recede if the West developed a relationship in which the Iranians believed they could live comfortably over the long term and in which the prospect of a military attack against Iran also recedes.

A focus on “breakout capability” and recitation of the mantra that “a bad deal is worse than no deal” overlook the enormous disincentives that Iran would have to renege on any agreement with the five permanent members of the U.N. Security Council and Germany — the “P5+1” — that helped to establish such a relationship. Iranian cheating would mean a redoubling of the political incentives in the West, and especially the United States, that have made it far easier for politicians to impose sanctions on Iran than to remove them. Iranians would be thrown right back into the economic vise they clearly want to be out of.

Reneging on an agreement also would go directly against the declaration of Iranian Supreme Leader Ayatollah Ali Khamenei that “production, stockpiling and use” of nuclear weapons are forbidden under Islam. A clear Iranian violation and movement toward a nuclear weapon therefore would involve almost as much of a loss of face for the supreme leader as it would for him to give up altogether Iran’s uranium enrichment program, as hard-liners in the United States and Israel unrealistically demand.

It would be a grave mistake for the United States and its partners to adhere to an inflexible negotiating position based on the mistaken notion that an Iran bent on building nuclear weapons can be coerced or physically prevented from doing so. If Iran really were bent on building the bomb, it probably would have done so by now, based on a nuclear program that dates to the time of the shah.

Certain prevention is impossible, whether through diplomacy, military force or other means. Like many other things in international relations, this issue is a matter of weighing relative risks. There is minimal risk of Iran throwing away an agreement that ended debilitating sanctions to pursue a nuclear weapons scenario that so far exists more in U.S. fears and politics than in Iranian desires.

The risk is much greater that an unbalanced, hard-line P5+1 position that offers only minimal sanctions relief while demanding substantial Iranian concessions would kill the best opportunity in years to build a better relationship with Tehran, would lose the additional scrutiny of Iran’s nuclear program that any conceivable agreement would include and would stoke Iranian officials’ interest in building a nuclear deterrent as a way of dealing with what they would perceive as unending Western hostility.

The task ahead is diplomacy in the fullest sense: the use of negotiations not to break the will of an adversary but, instead, to find enough common ground to reach agreements that both sides will want to uphold.