TIME | Lina Khatib: President Donald Trump’s sudden announcement in December that the U.S. would withdraw troops from Syria came at a time when Washington seemed to finally be developing a strategy to tackle the Syrian conflict that went beyond prioritizing fighting ISIS. It was not Syria that was the focus of this new strategy; it was Iran. While former President Barack Obama had pursued a softer approach to Iran that used the nuclear deal as a means of warding off potential Iranian threat to Israel and to nudge Iran towards playing by international rules, Trump views Iran as a destabilizing source in the Middle East.

Until he made the announcement about the US withdrawal from Syria, Trump had cast Syria as one of Iran’s venues for regional destabilization. His appointment of Ambassador James Jeffrey — who under George W. Bush had served as deputy national security advisor with a special focus on Iran — in August 2018 as Syria Special Envoy sparked the design of a U.S. strategy for Syria that foregrounded Iran. Two key components of this strategy — masterminded by Jeffrey — are increasing economic pressure on Iran to force it to roll back its activities in the region, and keeping American troops in Syria to limit both Iran’s access to oil fields in northeast Syria and its activities on the strategically important neighboring border with Iraq.

The withdrawal announcement put a stick in that wheel. A hasty withdrawal would empower Iran not just in Syria but also more widely.

Trump justified the announcement as delivering his election campaign promise to bring back troops from Syria. But implementing this promise before a resolution to the Syrian conflict is reached is akin to shooting oneself in the foot. Trump’s declaration on Jan. 2 that Iran “can do what they want in Syria” shows that he has come to regard Iran’s actions in Syria as distinct from its other regional activities. Yet, an imminent U.S. withdrawal from Syria would end up contradicting another of Trump’s very own campaign promises, which is to stand up to Iran’s influence in the Middle East.

After a meeting with Senator Lindsey Graham, Trump appeared to backtrack on the timing of the withdrawal, adding on Jan. 2, that the withdrawal would actually happen “over a period of time.” Graham and Trump may not see eye to eye on a number of issues — Saudi Arabia being one — but they are aligned on wanting to weaken Iran’s regional influence. Graham was one of the vocal opponents to the nuclear deal and strongly supported Trump’s decision to withdraw from it. In May 2018, Graham’s statement that “Iran has used the funds provided by the sanctions relief to enhance their military capability and create havoc throughout the Middle East” could have been taken from the Trump election campaign book. But any progress on the timing of the withdrawal as a result of the meeting with Senator Graham would be annulled by Trump’s isolating Syria from the wider regional context.

The area in northeast Syria where U.S. troops in Syria are deployed is highly coveted by Iran. It is rich in oil and is near the border with Iraq through which Iran has been sending into Syria its allied Iraqi Popular Mobilization Forces (PMF) militias under the pretext of fighting ISIS. It is in Iran’s interest for the Syrian-Iraqi border to be porous.

The presence of American troops in the area limits these militias’ freedom of movement. It also blocks Iran’s access to the area’s oil fields. As things currently stand in Syria, were the U.S. to withdraw from the north-east, Iran will be able to use the area’s oil revenue to offset some of the economic losses it is incurring following the American reinstatement of sanctions after Trump pulled out of the nuclear deal.

Some see in Trump’s announcement an expectation that Russia and the Bashar Assad regime would eventually veer away from Iran. This expectation is based on Russia’s growing competition with Iran over influence in Syria and the pro-Assad camp’s preference for Russia over Iran because Russia channels its influence through strengthening state institutions in Syria, in contrast to Iran’s approach to achieving influence through keeping Syrian state institutions weak. But neither Russia nor the Assad regime is able to completely reign in Iran’s activities in Syria. Their partnership with Iran can loosen in the long run if pressure on Iran in Syria increases and it becomes more of a liability than an asset for its two current allies. An imminent U.S. withdrawal, however, would give Iran time and space to consolidate its presence and access to resources and eventually make it more difficult for Russia and Assad to detangle Syria from Iran. This would be bad news for Israel’s security.

This was not the first time that Trump made a hasty announcement that alarms Israel. In March 2018, Trump had made a similar declaration about withdrawing from Syria, only to change his mind 48 hours later following intensive lobbying by pro-Israeli advisors in his close circle who, according to sources in Washington, managed to convince him that the time was not yet ripe for such a move because Israel’s security would be at stake.

The U.S. withdrawal could also give ISIS an opportunity to regenerate. According to the French Minister of Defence, allies of the United States in the international anti-ISIS coalition will not be able to realistically or effectively continue the work of the coalition on their own. This would also be the end of the Syrian Democratic Forces, the Kurdish-majority local Syrian forces who are the coalition’s partners in the battle against ISIS. They would be left to fight ISIS without crucial American ground support while also being vulnerable to attack by Turkey, which considers them to be linked with the Turkish terrorist-classified Kurdish group, the PKK.

Such developments can only pave the way for ISIS to take advantage of this vacuum. The more resurgent ISIS becomes, the more reasons Iran has to increase the number of its affiliated militias that are sent to Syria to fight ISIS (and with no U.S. troops standing in the way), especially with the PMF now playing a lesser military role in Iraq after the general military defeat of ISIS there. A more active PMF, in turn, would strengthen Iran’s position in Iraq as well.

Withdrawing U.S. troops from Syria imminently would weaken America’s anti-ISIS coalition allies, grant a lifeline to ISIS, threaten Israel, and empower Iran. In the end, it would undermine Trump’s own promises and goals, boosting Iran’s fortunes instead.