Nuclear talks between Iran and world powers have stalled, raising concerns that the negotiations may fail, comprehensively killing the 2015 nuclear deal. If this happens, the chances of resolving the Iranian nuclear crisis and reducing hostilities between Tehran and the west will be lost for many years, while critically harming diplomatic opportunities to resolve regional crises. The agreement — known officially as the Joint Comprehensive Plan of Action (JCPOA) — was the product of 12 years of intensive negotiations, and the most comprehensive non-proliferation deal in history. When I was a member of the Iran nuclear negotiating team in the early 2000s, we were on the verge of an agreement with the UK, France and Germany, which failed because of US opposition. Ten years later, with Washington on board, Tehran implemented its commitment to limit nuclear activities for three years until Donald Trump disastrously decided to withdraw unilaterally from the agreement in 2018. The Trump administration also mounted a “maximum-pressure campaign” to actively dissuade Britain, France, Germany and other EU members from engaging in trade and business with Iran. In response to this withdrawal of the JCPOA’s agreed trade benefits, Tehran began to exceed its agreed limits both on uranium stocks and enrichment levels. Joe Biden has tried to negotiate a return to the JCPOA on the basis that the US will lift sanctions and Iran will return to full compliance, including lowering enrichment levels from 60 per cent to below 5 per cent. Negotiations began in Vienna last April and a 20-page draft deal was agreed. However, a major obstacle to reviving the JCPOA remains: Iran’s demand that the US lifts Trump’s designation of Iran’s powerful Islamic Revolutionary Guard Corps as a foreign terrorist organisation. In retaliation, Tehran placed the US Central Command — America’s top military entity focused on the Middle East — on its own list of terrorist groups. Iran insists that, until the US designation is removed, the deal cannot be rescued, pointing out the IRGC was not classified as a terrorist group when the original deal was signed. Conversely, Israel, which is not a party to the deal, argues the IRGC should stay on the list. So do many in Washington. Last week, the US Senate overwhelmingly passed a non-binding resolution prohibiting the Biden administration from removing the terrorist designation on the IRGC in exchange for a revival of the deal. It also approved a motion from senator Ted Cruz suggesting that terrorism sanctions should be imposed on the Central Bank of Iran and the IRGC to limit co-operation between Iran and China. These Senate actions signal clearly to Tehran that any JCPOA revival will probably be shortlived. The US congressional election is only six months away and the Republicans — who look likely to win the majority — have stated they will do everything they can to block the JCPOA; some have said they would tear it up. This leaves little realistic hope for the agreement in the long term. As it stands, there are two possible scenarios. In the first, if the deal is not re-established, the US will most likely return to the Trump administration’s maximum-pressure strategy together with western countries and Arab states in the Gulf. This would drive Tehran further towards Russia and China. Iran would increase the capacity of its nuclear programme, including enrichment of uranium to weapons-grade levels as protection against a US or Israeli military strike. In the second scenario, simultaneous and reciprocal lifting of the IRGC and Centcom terrorist designations could reduce tensions and help to resolve the current deadlock. Concerns in Israel and the Persian Gulf could be addressed through regional talks. The fact is that Iran’s Quds force — the elite branch of the revolutionary guard — and Centcom have played a central role in the region. Without co-operation, the chance for resolving regional crises peacefully would be critically undermined. Iran and Saudi Arabia have already held a fifth round of direct talks in Baghdad. Iran’s Supreme National Security Council reached important agreements with Saudi Arabia’s intelligence chief. Co-operation and peace among the Gulf countries, especially Iran and Saudi Arabia, could prove critical in resolving their proxy battles in the region, including Yemen, Syria, Lebanon, Iraq and Libya. Sustainable peace, stability and security in the Gulf and the Middle East will not be possible without a system of co-operation and collective security. Now is the time for diplomats on all sides to redouble their efforts in pursuit of that goal.