Goodbye, Iran deal—we hardly knew you. On Tuesday afternoon, U.S. President Donald Trump signed an order to pull out of the “decaying and rotten” nuclear agreement signed with Iran in 2015.

Known officially as the Joint Comprehensive Plan of Action, or JCPOA, the deal made Iran freeze nuclear development under an international inspections regime in return for sanctions relief. It was the crowning achievement of years of multilateral diplomacy under Trump’s predecessor, Barack Obama, who has termed the withdrawal “a serious mistake.”

Apart from the United States and Iran, the JCPOA had also been signed by the United Kingdom, France, China, Russia, and Germany, all of whom criticized the American move to withdraw. In theory, the JCPOA could live on without the United States, which French Foreign Minister Jean-Yves Le Drian said it will. But the direct and second-order effects of resumed U.S. sanctions are so severe that Iran may see sharply reduced benefits in maintaining its nuclear freeze.

As expected, Iranian President Hassan Rohani slammed Trump and said he had ordered preparations to “resume the enrichment at the industrial level,” though he added that he will first spend a few weeks consulting EU signatories. Rohani may simply be studying the situation, but hedging is also a logical response for a president that likely hopes to preserve at least some of his country’s newly budding trade ties and keep international sympathy on Iran’s side, whatever happens next.

Trump had hinted at the possibility of a new, more “constructive” deal, which would include “efforts to eliminate the threat of Iran’s ballistic missile program, to stop its terrorist activities worldwide, and to block its menacing activity across the Middle East.” But he also said he expects Iran to continue rejecting the idea of renegotiation, adding, “I’d probably say the same thing if I was in their position.”

That’s little consolation for Rohani, but one can expect European leaders to dive for the idea of a new JCPOA to take the place of the old one.

A New Round of Regional Escalation?

With little apparent readiness for a new and renegotiated deal, Trump’s decision may instead inaugurate a new round of escalation and conflict in the Middle East. The United States is closely aligned with Tehran’s enemies in Israel, Saudi Arabia, and the United Arab Emirates—all of whom cheered Trump’s decision. These nations have locked horns with Iran all over the Middle East in recent years, creating plenty of triggers and tripwires for regional escalation.

For example, the Arab Gulf states sent troops to Yemen in 2015 to fight the Iran-backed Houthi movement. Though the United States gave tepid support at first, it may now be wading deeper into the war. The New York Times recently revealed that U.S. Marines are operating on the ground along the Saudi–Yemeni border.

Iran–Israel conflict could also flare up in the absence of a political horizon and international pressure for restraint. Right as Trump pulled out of the nuclear deal, CNN reported that Israeli and American officials fear Iran might be seeking to stage attacks in Israel; the Syrian military then reported Israeli missile strikes on targets in the Damascus area.

Israel’s occupation of Palestine is one arena in which the rivalry plays out. While Israel is a close U.S. ally and Washington has ties to Palestinian groups in the West Bank, Iran is more entrenched in the Islamist-ruled Gaza Strip. In the past couple of years, Tehran has largely repaired relations with Hamas after a cold spell caused by the war in Syria, and it also maintains ties to smaller Islamist factions like Islamic Jihad and Sabireen.

Rival groups working under the Palestine Liberation Organization umbrella, including the Fateh Movement of Palestine’s aging and unelected president, Mahmoud Abbas, are at a strategic dead end after the failure of the peace process. They were publicly humiliated by Trump’s decision to recognize Jerusalem as the Israeli capital (but not also that of Palestine), and they’re in for more of the same as Trump’s son-in-law Jared Kushner prepares to unveil his “deal of the century.”

With the eighty-two-year-old Abbas now having nothing to offer politically and lacking an agreed-on successor, and Palestinian refugee camps at risk of falling apart economically due to U.S. cuts in UNRWA funding, the situation is ripe for Iranian exploitation.

Iranian–Israeli Tension in Lebanon and Syria

Iran and Israel also clash in Israel’s neighbors, Lebanon and Syria.

In Lebanon, Iran is represented by Hezbollah, which advanced its influence over local politics in the May 6 elections. Israel–Hezbollah tensions tend to ebb and flow, but while Israel managed to enforce several years of calm along its northern border through a brief but brutal 2006 conflict that dealt extensive damage to Lebanon, talk of war has crept back into the conversation since 2011.

The situation in Lebanon is inextricably linked to the Syrian conflict next door, where Iran, Hezbollah, and other proxies of Iran’s Islamic Revolutionary Guard Corps (IRGC) fight on the side of President Bashar al-Assad. The Iranian government has also helped prop up Assad’s government by offering generous loans and credit lines.

Should U.S. sanctions snap back in place, the costs of Tehran’s military investments will come into relief for the Iranian government and public, where there is clearly some discontent over the billions spent on Syria during a time of domestic economic distress. But Iran fought for Assad without flinching before the Iran deal, and Assad’s position has by now been dramatically improved, not least because Russia has entered into the war on his side. Still, the marginalization of opposition forces has led the conflict to a new stage characterized by direct international intervention. In particular, Israeli and Iranian interests rub up awkwardly against each other in southern Syria, where Israel has occupied the Golan Heights since 1967.

The lack of established ground rules and buffers—in Lebanon, for instance, UNIFIL peace monitors serve as a channel for indirect communications—means Syria is an untested, risky flashpoint for an Iran–Israel conflict. The International Crisis Group’s Joost Hilterman recently argued in a New York Times op-ed that Russia, which talks to all sides, should take the lead on creating de-escalatory institutions in southern Syria. Whether Moscow has the wherewithal and energy needed for that thankless task is another matter.

Trial Number One: Iraq

The first arena of renewed U.S.–Iranian contest is likely to be Iraq, where elections on May 12 will shape the country’s post-Islamic-State future.

Since 2014, Iran has strengthened its hand in Iraq by building up proxies within the militia alliance known as al-Hashd al-Shaabi. The powerful Hashd figure Hadi al-Ameri has gathered commanders in an electoral alliance on a pro-Iran, anti-America platform. Washington and Riyadh instead root for Prime Minister Haider al-Abadi, a pragmatic figure with the institutional benefits of incumbency and some cross-sectarian appeal. However, Abadi will likely be forced to cut deals with pro-Iranian hardliners and other Shia Islamist figures if he hopes to secure a second term.

Iran has a thousand and one ways of making life difficult for America and its allies in Baghdad, but, unlike in Syria or Lebanon, the United States is well equipped to push back. Both are likely to view the post-election wrangling as a zero-sum game, tempting them to deploy rough pressure tactics and other skulduggery.

The Iran deal did not bring U.S. and Iranian policies into alignment in Baghdad, but its collapse could well be reflected in intensified competition over Iraq’s future.

Dealing with the Lack of a Deal

Regional and international actors are still trying to figure out what Trump’s decision means, and it is too early to tell how JCPOA signatories will bounce off of each other as they all begin to adjust their policies. But sooner or later, the deal’s defenders will likely have to accept that they lost that battle.

American–Iranian relations have taken a leap into the unknown, and the Middle East is being dragged along with them.

Though Europeans, Russians, Chinese, and Iranians may want to explore ways to revive the deal, or at least keep it on life support with an eye to the U.S. presidential elections in 2020, their more urgent task will likely be to treat the second-order effects of the deal’s collapse. American–Iranian relations have taken a leap into the unknown, and the Middle East is being dragged along with them.

This work was supported by a research grant from The Harry Frank Guggenheim Foundation.