America has never known so little about a president-elect. After Trump ran a campaign almost completely void of substance, speculation about his positions regarding key national security issues is doomed to be based on nothing more than slogans and tweets. We do know, however, that he has a mandate to unravel much, if not all, of Barack Obama’s legacy — including the historic Iran deal.

Make no mistake, the Iran deal is under severe threat. Trump has referred to it as “the worst deal ever negotiated,” and promised at the American Israel Public Affairs Committee’s conference this year that his first priority would be to “dismantle” the agreement.

The Iran deal was already on fragile ground, and frankly, even a Hillary Clinton victory would have increased its vulnerability. But with Trump, its fate is arguably more complicated than it would have been with a victory by Marco Rubio or Ted Cruz — two Republican senators who, unlike Trump, promised to tear the deal apart on their first day on the job. Trump has “only” vowed to renegotiate the deal — a completely unrealistic option — while simultaneously complaining that the deal did nothing to lift America’s primary sanctions on Iran (the ones that prevent Trump’s own companies from doing business with Iran).

Even if Trump intends to unravel the deal, his options to do so directly are very limited. It is, after all, not a bilateral deal with Iran that he is in a position to void on his own, but one that also includes Russia, China, France, the United Kingdom, and Germany, codified in a U.N. Security Council resolution. 

Trump’s far more likely path to unravel the deal would be to add political risk to any Western companies contemplating entry into the Iranian market. Businesses have already been hesitant to enter the Iranian market, partly on the fear that the United States did not have the discipline to refrain from imposing new sanctions on Iran, and thus force companies that just entered the Iranian market to exit it once again, at a hefty cost. By instilling doubt about the durability of the deal, businesses will tend to avoid entering Iran in order to evade the cost and embarrassment of having their deals sabotaged by new potential sanctions.

In such a scenario, Iran would not be able to reap any economic benefits from a nuclear deal that was technically still in effect. Disappointment in the agreement is already quite extensive in Iran, as many Iranians expected economic conditions to improve quicker after it went into effect. This is a significant threat to the deal, because if the dissatisfaction festers, President Hassan Rouhani’s prospects for reelection in 2017 will dwindle.

There is, in other words, the prospect of a vicious cycle that works against proponents of the Iran deal. If Rouhani loses, one of the agreement’s strongest supporters will no longer be there to ensure Tehran’s continued commitment. Even if the absence of de facto sanctions relief doesn’t impact Rouhani’s reelection bid, the likelihood of Tehran seeking an exit from the deal will nevertheless increase, as the restrictions on its nuclear program will be indefensible politically,

If Trump returns to a general policy of isolating in the region diplomatically and economically, he might find it easier said than done. It will require the intricate work of building an international coalition against Iran, which a Clinton administration — that was likely to adopt a similar policy — may have been adept at, but which Trump may be unable to pull off. For instance, the Obama administration only succeeded in assembling a strong coalition against Iran after first having convinced the international community that Iran was at fault in failing. But today, it isn’t Iran that is speaking of dismantling or renegotiating the deal. It is Trump and the GOP.

This is partly why some hard-liners and moderates I have spoken to in Iran favored a Trump victory. From their perspective, the choice was between two equally hostile American presidential candidates: One who has a track record of building strong coalitions against Iran versus one who has little to no international experience at all.

There is also a chance, of course, that the Trump administration will not be nearly so dire for U.S.-Iranian relations.

Following that logic, Trump did acknowledge that Tehran is knee-deep in the fight against the extremist organization. “I don’t like Assad at all, but Assad is killing ISIS,” Trump said during one of the debates. “Russia is killing ISIS. And Iran is killing ISIS.” Notably, he did not mention Saudi Arabia or the United States’ other traditional allies in the Middle East. If his priority in the region is defeating the Islamic State, he will not only need collaboration with Russia and Iran, he will also need to sustain the Iran deal in order to avoid a deterioration of ties with Tehran that inevitably would affect the struggle against the group.

Still, we know too little about Trump to be able to determine the priority he would give to Iran, the Islamic State, or the nuclear deal. We know more about the track record and inclinations of some of his allies and potential cabinet members, such as Newt Gingrich and Rudy Giuliani, whose support for the Iraq War was as steadfast as Trump’s campaign-long claim that he had been opposed to the conflict. If Trump delegates foreign policy to some of these allies who do not share Trump’s presumed inclination for restraint, then a return to the George W. Bush’s approach to Iran may be more likely.

The United States and Iran’s relationship has always been complicated. Under President Trump, it will become even more so.

This piece originally appeared in Foreign Policy.