Observers are particularly puzzled over whether President Donald Trump will seek to alter or eliminate the nuclear pact with Iran, the Joint Comprehensive Plan of Action (JCPOA). Indeed, Trump expressed some very strong reservations about the Deal and, on occasion, promised to scrap it entirely. That said, Trump has had a history of making ambiguous and reckless comments on several issues, which may or may not finally constitute his Administration’s policy. His most recent position on the Iran Deal is that the JCPOA needs to be changed, but not totally discarded.

But the deal also involves countries other than the United States and Iran. The JCPOA was signed by Iran and the P5+1 countries (that is, the five permanent members of the UN Security Council and Germany) and cannot be unilaterally abrogated by the United States or any one of the signatories. There are strong indications that the other parties to the deal are strongly opposed to any alteration. The European Union, which was also part of the negotiations, has opposed changes to the agreement. In fact, Federica Mogherini, the EU’s foreign policy chief, recently took steps to close loopholes and clarify some oversight provisions in order to prevent the United States from charging Iran with non-compliance. It is not clear whether President Trump would listen to these reservations given his erratic track record, but if he decides to repeal the deal, there would likely be very strong backlash from the other signatories.

However, the Republican-dominated Congress offers a more realistic scenario of undermining the JCPOA. Congress already passed a number of new sanction measures, and is in the process of passing more sanctions-bearing bills in order to force Iran to negotiate a new agreement.

In principle, inflicting more economic pain on Iran through further sanctions should be easy to repeat. But it is not entirely clear whether the complex interplay of economic hardship, anomic behavior and delegitimization of Iran, which made the original nuclear deal possible, can be reproduced in the future through unilateral sanctions.

There is little appetite among Russia, China and even the West to engage Iran in another decade-long round of negotiations over its nuclear program. China and the EU are reluctant to abide by America’s unilateral new sanctions regime, and will resist American pressure due to their profitable trade relationship with Tehran. The unanticipated costs of sanctions make the P5+1 reluctant to follow the sanctions regime.

Having publicly expressed his admiration for Putin, Trump would find it hard to deal with Vladimir Putin's strong opposition to altering or discarding the deal. Further, Trump does not seem to be aware that by speaking out against the deal, he has put himself in opposition to Putin – making this one of the many contradictions in his foreign policy. Russia, which has flourishing bilateral ties with Iran, would adamantly oppose new international sanctions. Russia is also in the process of expanding its influence in the Middle East with considerable help from Iran, and this will make Putin's concession on the deal even less likely.

There is another interesting dynamic at play. On the one hand, Trump has disparaged the nuclear deal, while on the other, he considers defeating the Islamic State (ISIS) – a group against whom Iran has been one of the major combatants – his top foreign policy priority. This is quite typical of the built-in-contradictions in Trump's foreign policy. His overall approach to international relations is based on what is called ‘transactional diplomacy’ – an approach to diplomacy that is based on a series of deals with countries on select issues. This approach is often not sensitive enough to discern the underlying complexities stemming from the fact that international policies are interrelated.

There are other challenges arising out of Trump’s hostility towards the Iranian deal: scrapping the deal would intensify the power struggle in Iran, enabling hard-liners to defeat the more moderate President Hassan Rouhani with far reaching consequences. The Revolutionary Guards, the force in charge of the nuclear program, may well be inclined to block the IAEA from inspecting certain nuclear sites. Mohsin Fakhrizadeh, a rogue nuclear scientist and Brigadier General in the Revolutionary Guards, and Fereydoon Abbasi-Davani, the chief of Iran’s Atomic Energy Organization under former President Ahmadinejad, are positively in favor of the so-called “sneak out” strategy – a term which refers to clandestine efforts to produce a weapon in a parallel, undeclared facility.

Furthermore, a vengeful, hardline government in Tehran could use ISIS as a tactical weapon against American interests. It would not be the first time that the Iranian regime forges a tactical alliance with a sworn enemy of America. The 9/11 Commission Report concluded that the Revolutionary Guards sheltered senior members of Al Qaeda after they fled American forces in Afghanistan. Worse, American intelligence agencies believe that some Iran-based Al Qaeda terrorists acted as regime proxies in attacks against Americans. It would be possible for the Quds Force to employ ISIS in a similar capacity.

It is possible that Trump may realize that fighting ISIS requires the goodwill of Tehran – something that President Bush learned the hard way in Iraq when he encountered militias sponsored by Iran. But again, Congress may stand in his way and, unlike President Obama, Trump would not be able to veto fresh sanction measures due to partisan political considerations.

Given the grim implications of any of the above scenarios, the Trump administration should accept the nuclear agreement as it stands. But there are ways to squeeze the Iranian regime and tighten the pact. For instance, Washington could punish Tehran for its ballistic missile program. There are certainly some concerns about Iran’s long range missiles, since the cost-benefit analysis does not justify mounting conventional payloads. Clarifying and tightening Resolution 2231 in this regard would be a good way to start.

Trump should also punish the Iranian regime for its sponsorship of terrorism. Fortunately for Trump, both Gen. James Mattis and Gen. Michael Flynn have hawkish opinions on Iran, mostly for its involvement in terrorism. Both Generals view Iran as a leading sponsor of Islamist terrorism, either through the Quds Force, the foreign operation unit of the Revolutionary Guard, or numerous proxies ranging from the well-known Hezbollah to the less known units which operate virtually all over the Middle East.

As a Marine, Gen. Mattis is well aware that the Iranians sponsored the infamous attacks on the Marine Barracks in Beirut, the single most lethal assault on U.S. Marines in recent decades. For punishing Iran, the United States has an arsenal of tools, including covert operations and sophisticated cyberwar tools which can be used against the Iranian regime, in addition to options including revoking waiver of entering Iranian market from global companies.

Indeed, Iran hoped to cash in on the JCPOA’s promise of Foreign Direct Investment (FDI), especially as the country’s critical oil and gas sectors badly degraded under years of mismanagement and sanctions. Trump should make clear to the Iranians that he will not allow Iran access to the FDI market if Iran continues its sponsorship of terrorism.

Dr. Farhad Rezaei is research fellow at Center for Iranian Studies (IRAM) in Ankara where his research focuses on Iran's foreign policy. His writings have appeared in The National Interest, Middle East Policy and British Journal of Middle Eastern Studies among others. He tweets at @Farhadrezaeii