This post is one of three CERL blog articles that examine the Iran Nuclear Deal and the United States’ future role in it it. The views expressed in this article are those of the author and do not necessarily represent those of CERL or any other organization.

The Biden administration’s declared intent to rejoin the Joint Comprehensive Plan of Action (JCPOA, also referred to as the “Iran Nuclear Deal”) is an essential measure to stop Iran from building nuclear weapons and pave the way towards addressing other security threats posed by Iran. Failure to follow through on rejoining the deal would be a drastic mistake. The JCPOA is not a reward for Iranian behavior: it is an agreement that enhances U.S. national security.

Under the JCPOA, Iran eliminated 98% of its uranium stockpile, removed over 13,000 centrifuges, and destroyed the core of the Arak reactor by January 16, 2016. These steps effectively foreclosed Iran’s pathways to building nuclear weapons. Although Iran is currently in violation of the JCPOA, Iran remained in compliance and did not violate the JCPOA until the United States withdrew from the agreement. It is no surprise that once the United States rejected the JCPOA, Iran followed suit.

The U.S. withdrawal from the JCPOA has not only increased tensions with Iran, it has also strained the transatlantic relationship with European allies and undermined the ability of European partners—who have remained in the deal—to hold Iran accountable. Iran agreed to the JCPOA to gain relief from crippling international sanctions. By unilaterally reimposing sanctions on Iran (against the wishes of partners like Germany, France, and the UK), the United States removed Iran’s biggest incentive to remain in compliance with the deal. Furthermore, the U.S. withdrawal has empowered hardliners in Iran, who claim that the U.S. abandonment of the JCPOA proves that Iran should have never negotiated with the United States in the first place. Iranian opponents of the agreement are the biggest winners of the U.S. withdrawal from the JCPOA.

Critics of the JCPOA sometimes argue that because it is not a treaty ratified by the Senate, the agreement is unenforceable. Indeed, there is no higher authority to prevent parties from withdrawing or to punish them for violations. That, however, is true of nearly all international agreements operating in an anarchic system—whether they are Senate-ratified treaties or executive agreements. The lack of a higher authority does not mean that the United States and the other countries involved in the agreement are powerless to take action against Iran’s violations. Instead, it means that the states that negotiate agreements must enforce them. The lack of an international enforcement body for other international agreements, such as the Hague Code of Conduct on Ballistic Missile Proliferation or the Biological Weapons Convention, has not led to calls for the United States to withdraw from these agreements. Nor has it prevented the United States from addressing issues of suspected violations. It is not clear why the JCPOA would be different from other international agreements in this regard.

Importantly, the JCPOA provides a highly intrusive inspection regime to verify Iran’s compliance with the agreement. If Iran continues to violate the agreementthe other parties to the JCPOA will know—just as they have so far. Rejoining the JCPOA provides the United States with greater inspection and accountability tools to ensure Iran is not building nuclear weapons and to catch Iran if it attempts to do so. It also gives the United States greater international legitimacy to take more aggressive action if Iran develops nuclear weapons.

Outside the JCPOA, what options remain for the United States to stop Iran from building nuclear weapons? Threats of coercion—threatening a war that no one wants, including the United States—have failed to keep Iran in compliance with the JCPOA, let alone produce a stronger deal in the wake of U.S. withdrawal from the agreement. Pressure from multilateral sanctions successfully brought Iran to the negotiating table, but U.S. retaliatory unilateral sanctions have failed to produce a replacement agreement or stop Iran from ramping up its nuclear program once the United States withdrew. The Trump administration’s ‘maximum pressure’ campaign has overwhelmingly failed to produce concessions from Iran. Instead, in the words of one analyst, it has produced a reaction of “maximum resistance.” In response to the United States’ withdrawal from the JCPOA and subsequent reinstatement of nuclear and other sanctions, Iran has steadily reduced its compliance with the JCPOA: increasing its uranium enrichment, advanced centrifuges, and stockpile size. Moreover, maximum pressure has failed to stop Iran from supporting proxies that further destabilize the region and has strengthened domestic hardliners. Provocations—like the assassinations of an Iranian general and a top Iranian nuclear scientist—have only further galvanized Iran’s parliament to aggressively pursue efforts to increase uranium enrichment and implement even less of the JCPOA.

The JCPOA does not address all threats Iran poses to international peace and security, and it was never intended to do so. The agreement was designed to counter the greatest threat Iran poses to the United States—by closing pathways for Iran to build nuclear weapons. Walking away from the JCPOA has made it harder to secure a follow-on deal that would extend the agreement’s timeline and address Iran’s ballistic missile program, its support for terrorism, or other challenges that destabilize the Middle East. For the United States to have any hope of addressing these security challenges in a future deal, it must first show that it is credibly committed to the JCPOA. If the United States negotiates agreements only to reject them a few years later, why would Iran (or any country) continue to negotiate with the United States? Rejoining the JCPOA does not guarantee a future deal that addresses additional concerns but failing to do so is a surefire way to prevent a future deal. Rather than accepting U.S. withdrawal from the JCPOA as the new status quo, the Biden administration should rejoin the most effective tool the United States has to stop Iran from building nuclear weapons and counter the security threats Iran poses.

The United States has a long history of negotiating with adversaries to successfully pave the way for future agreements. To take an example from U.S.-Soviet arms control, the 1972 SALT I interim agreement limited the risks of nuclear war by capping each side’s number of delivery vehicles. Although it was a remarkable achievement in its own right, it also paved the way for subsequent arms control agreements that were more expansive and had deeper verification provisions, including the 1991 START treaty and the 2010 New START treaty. It was also a critical tool for the United States to establish détente and transform the political relationship between the two countries. During the SALT I negotiations, U.S. negotiators pursued an agreement that was actually attainable, rather than seeking an agreement that would cover every aspect of the Soviet military. Negotiating with adversaries is not a sign of weakness but an important tool to protect and advance U.S. national security. Like the JCPOA, U.S.-Soviet arms control was not built on blind trust but on careful assessments of whether the Soviet Union was implementing its obligations under arms control agreements.

Although there are clear differences between Iran and the Soviet Union, the model of negotiating with adversaries over what is possible rather than seeking an impossible deal is as applicable today as it was in the 1970s. In both cases, this approach has produced clear results that have reduced security threats to the United States. Both bilateral U.S.-Russia (or U.S.-Soviet) arms control and the JCPOA exemplify the art of the possible. Negotiating with adversaries may be distasteful but is often necessary to reduce the threats they pose to the United States. To dismiss negotiations with adversaries on principle is to undermine U.S. national security.

Rejecting the JCPOA in hope of attaining something better was and continues to be a fantasy. The JCPOA offers the best path for the United States to prevent Iran from building nuclear weapons and was working until the United States withdrew. The reality today is much starker, and Iran is closer to building a nuclear weapon. The steps Iran has taken in violation of the JCPOA, however, are reversible—Iran can return to compliance with the deal. In fact, Iran recently stated that it will reestablish full compliance upon the United States’ return to the deal. Although such compliance must be verified, a U.S. return to the JCPOA is the best way to incentivize Iran to comply with the deal. Moreover, the only way to achieve another agreement in the future—including one that addresses Iran’s ballistic missile program and other security threats Iran poses—is for the United States to return to the JCPOA and implement its part of the deal. Rejoining the JCPOA advances U.S. national security, restores U.S. credibility, and should be a top priority for the Biden administration.

Naomi Egel, a Ph.D. candidate at Cornell University, is the Janne Nolan Nuclear Security Visiting Fellow at the Truman Center for National Policy and the Truman National Security Project, where she leads Truman’s policy engagement on nuclear issues. Twitter: @NaomiEgel