Iran’s Supreme Leader Ayatollah Ali Khamenei said on January 8 that Tehran was in no rush for the United States to rejoin the 2015 nuclear deal formally known as the Joint Comprehensive Plan of Action (JCPOA), but, he also said, sanctions on Iran must be lifted immediately. “If the sanctions are lifted, the return of the Americans makes sense,” he insisted. President-elect Joe Biden has announced his plan to return to the deal soon after he is sworn into office. “If Iran returns to strict compliance with the nuclear deal,” he wrote in an op-ed for CNN, “the United States would rejoin.” His Iranian counterpart, President Hassan Rouhani, has also expressed willingness to return to the deal, stating that, “Iran could come into compliance with the agreement within an hour of the United States doing so.”

Five years ago, after years of intensive negotiations, six world powers managed to sign the world’s most comprehensive nuclear agreement with Iran. While the agreement was a political one, it was also ratified by the UN Security Council in Resolution 2231. And, according to the International Atomic Energy Agency (IAEA), the organization tasked with verifying the agreement’s technical aspects, Iran was fully complying with the deal for about three years, until President Trump withdrew from it in May 2018. In response to the US violations of the nuclear agreement, Iran too reduced some of its commitments. Most recently, on January 4, Iran announced that it had increased its uranium enrichment levels to 20 percent.

Although reviving the agreement is certainly still possible, it won’t be easy. The two sides will need to overcome nine hurdles to make it happen.

First, the sequencing of a mutual return could be an immediate problem. Iran expects the United States to lift sanctions first, because it  was the Trump administration that withdrew first. While Tehran’s demand is legitimate, Washington may ask that Iran come into full compliance before lifting sanctions. Indeed, a straightforward reading of the quotation from Joe Biden’s op-ed suggests just that. In this scenario, after Joe Biden’s executive order rejoining the deal, Iran and the world powers can meet and agree on a realistic plan with a specified timeline of proportionate reciprocal actions.

Second is the issue of what compliance constitutes. During the Obama administration there was one major barrier to the full realization of the terms of the agreement: Many US primary sanctions, targeting US citizens and permanent residents, organizations, and individuals that engage in trade and business with their Iranian counterparts, remained intact. These sanctions limited the economic benefits of the deal for Iran. The 29th paragraph of the deal clearly states that all signatories will refrain from any policy specifically intended to directly and adversely affect the normalization of trade and economic relations with Iran. This cannot be achieved without abolishing the primary sanctions.

Third, the Trump administration imposed numerous sanctions against Iran under the guise of terrorism and human rights, aimed at preventing the Biden administration from returning to the deal. For a clean implementation of the agreement, Biden will need to remove all of these sanctions as well.

Fourth, Trump’s withdrawal from the agreement and violation of the UN Security Council Resolution 2231 as well as other international commitments has damaged US credibility abroad. There is now a widespread belief among policy makers in Iran that the United States will simply not live up to its end of the bargain, no matter what that bargain is. This naturally raises the important question: What guarantees are there that the United States will remain committed to the deal in the post-Biden era?

Fifth, because of Trump’s maximum pressure policy, the Iranian economy has suffered hundreds of billions of dollars of losses while Iran was in full compliance with the terms and conditions of the deal. Some Iranian leaders, including Iran’s foreign minister Mohammad Javad Zarif, have demandedcompensation for the economic damage the country suffered after the United States withdrew. The challenge will be to find a mechanism to compensate for the economic damages that the Trump administration inflicted on the Iranian economy.

Sixth, the “snapback” mechanism built into the agreement allows any country to force the UN Security Council to reimpose multilateral sanctions against Iran if Iran fails to fulfill its commitments. But this is one-sided: There is no such remedy for Iran if other parties fail to do their part. This became abundantly clear when the Trump administration first withdrew from the deal and then tried to unilaterally re-impose multilateral sanctions on Iran through the snapback mechanism. It was as if the injurer was demanding punishment for the injured. Although the UN Security Council rejected the US demand, the stunt revealed the structural flaw of the snapback.

Seventh, in the first week of December 2020, the Iranian parliament passed a bill mandating Iran’s Atomic Energy Organization to resume enriching uranium to 20 percent purity. The legislation also requires the Iranian government to cease voluntary implementation of the IAEA’s Additional Protocol within two months of the bill’s enactment if the other signatories fail to fully deliver on their commitments under the agreement. And after three months, the Atomic Energy Organization is obliged to begin using at least 1,000 second generation centrifuges. In short, president-elect Biden will need to move fast.

Eighth, there are some in the United States who are worried that Trump may start a reckless last-ditch war with Iran before leaving office. While this concern is overblown, there should be no doubt that US partners in the region will do whatever they can to prevent Biden’s return to the deal. Israeli Prime Minister Benjamin Netanyahu has already said as much. To be sure, the hardliners in Iran are also fundamentally opposed to the deal.

Ninth, some pundits and politicians in Washington want Biden to leverage the Trump administration’s sanctions to pressure Iran to accept additional commitments beyond the original agreement as a condition for US return to compliance. These include limiting Iran’s missile capability, extending the so-called “sunset” clauses within the deal, or resolving regional disputes. But from Iran’s perspective, such demands are a non-starter. As the spokesperson for Iran’s foreign ministry said recently, “No negotiation has been, is being, or will be held about Iran’s defense power.”

Despite these hurdles, Biden should nevertheless seek a reentry into the deal. Only a clean and full implementation by all parties can save the world’s most comprehensive nuclear agreement, contain rising US-Iran tensions, and open the path toward more confidence building measures. That path should include, upon Biden’s issuing an executive order to rejoin the JCPOA, the creation of a working committee of parties to the agreement tasked with ensuring full compliance by all signatories, and a forum, organized by the UN secretary general, in which Iran and the Gulf countries can discuss a new structure for improving security and cooperation in the region.