1. Deal survives The deal’s supporters and the Trump administration convince Congress not to reimpose, or “snap back”, US nuclear sanctions on Iran, which would put Washington in violation of the agreement and risk triggering its collapse. Congress also amends legislation that requires the president to certify whether Iran is in compliance with the deal every 90 days, extending the certification timeframe or changing criteria. This would give Mr Trump a way out of having to publicly declare Iran is not in breach of an agreement he has described as the “worst deal ever”. A smooth ride also means convincing Mr. Trump to waive a congressional requirement, mandated by an act he signed into law in August, to designate Iran’s Revolutionary Guards as a terrorist organization by October 30. Tehran has suggested that if Washington targeted the Guards, one of the Islamic republic’s most powerful forces, it would consider it a termination of the agreement. 2. Renegotiation Congress does not vote to reimpose sanctions and the US stops short of falling out of the deal, but Washington attempts to renegotiate it. The Trump administration uses the uncertainty to press European allies to lean on Iran to fix what it believes are the deal’s flaws and to adopt a harsher strategy towards the Islamic republic. European signatories maintain the deal cannot be altered but push for

2. Renegotiation Congress does not vote to reimpose sanctions and the US stops short of falling out of the deal, but Washington attempts to renegotiate it. The Trump administration uses the uncertainty to press European allies to lean on Iran to fix what it believes are the deal’s flaws and to adopt a harsher strategy towards the Islamic republic. European signatories maintain the deal cannot be altered but push for stricter interpretation of the rules and greater access to military sites. They suggest ways to address the Trump administration’s concerns beyond the scope of the agreement itself, such as starting talks to address a new arrangement to cover the period after 2025, when the deal is due to expire, or Iran’s ballistic missile programme. The Senate lends support to any tougher strategy pursued by Mr Trump in a non-binding resolution. The US drags its heels on a deal for Boeing to sell $20bn of aircraft to Iran and imposes new non-nuclear sanctions against the Islamic republic but stops short of designating the Revolutionary Guards a terrorist organization. Uncertainty over US international commitments following decertification makes it harder to work with European allies to address Iran’s regional activities and for the US to move towards talks with North Korea. Iran argues that the US has undermined the deal by stymieing much needed foreign investment into the Islamic republic and pursues actions against US interests in the region, including in Syria, Lebanon, Yemen, and Iraq. Regional instability increases. 3. Back to sanctions Congress reimposes nuclear sanctions, prospects for the deal’s survival diminish and the US is criticised for being the unilateral aggressor against the agreement. Allies accuse Washington of failing to live up to international accords and the Trump administration’s touted preference for talks with North Korea falls on fallow ground.

3. Back to sanctions Congress reimposes nuclear sanctions, prospects for the deal’s survival diminish and the US is criticised for being the unilateral aggressor against the agreement. Allies accuse Washington of failing to live up to international accords and the Trump administration’s touted preference for talks with North Korea falls on fallow ground. Mr Trump designates the Revolutionary Guards a terrorist organization, which Tehran regards as a hostile act and a sign that Washington is moving towards regime change. Europeans introduce so-called blocking legislation in an attempt to insulate their business operating in Iran from US sanctions. But the promised economic dividend of the deal is further undermined. Efforts to keep the accord alive without the US fail, Iran is free to pursue nuclear enrichment unfettered and with better know-how. Tensions escalate in the Middle East.