The Iraqi parliament voted Sunday to expel US troops from the country in response to the US killing top Iranian official Maj. Gen. Qassem Soleimani at Baghdad’s airport on Friday.

The vote — which was on a resolution for the expulsion of US troops backed by interim Prime Minister Adel Abdul Mahdi — marks one of the first concrete consequences of the strike that experts predict will dramatically shift political relations in the region.

Some Iraqi officials — including Mahdi — have complained that the US’s attack on Soleimani violated Iraqi sovereignty. In a Sunday speech before parliament recommending a “yes” vote on the resolution, Mahdi told lawmakers President Donald Trump spoke to him ahead of the strike and failed to mention it, according to the Washington Post’s Mustafa Salim. Mahdi said he also explicitly told Trump the US was not to bring additional US military resources into the country.

In response to the attack on Soleimani — which killed other leaders as well, including militia leader Abu Mahdi al-Muhandis — Mahdi told lawmakers, “I put to the Parliament two options: one, ending the existence of these forces immediately and start the immediate arrangements for this; two, set a timeline for the departure of these forces.”

The prime minister continued: “I recommend the first option and keep the friendship between US and Iraq. It’s [in] the interests of Iraq and US to reorganize the relationship between both sides in a way keeps the sovereignty of Iraq.”

Lawmakers accepted this recommendation, approving a resolution that read, in part: “The Iraqi government must work to end the presence of any foreign troops on Iraqi soil and prohibit them from using its land, airspace or water for any reason.”

Expulsion is not yet a certainty

The passage of the resolution, however, does not mean foreign forces will immediately be expelled from the country. The country’s prime minister would need to sign off on a formal bill to accomplish that. Mahdi, of course, supports the move, but the fact that he is an interim prime minister could complicate matters.

US Secretary of State Mike Pompeo seemed to suggest the fact that Iraq’s government is in transition could keep US troops on the ground for now, on CBS’s Face the Nation Sunday, and made it clear the Trump administration does not want to comply with the resolution.

“It is the United States that is prepared to help the Iraqi people get what it is they deserve and continue our mission there to take down terrorism from ISIS and others in the region,” Pompeo said, stressing that it is the acting prime minister who has endorsed the expulsion. “That is in defense of the Iraqi people and is good for America, too.”

Will the U.S. comply with Iraqi parliament requests to remove nearly 5k American troops in Iraq? @SecPompeo suggests U.S wants to keep troops overseas. WATCH → pic.twitter.com/cqWsahvMOc — Face The Nation (@FaceTheNation) January 5, 2020

Mahdi tendered his resignation in November, following mass protests, but he has yet to be replaced, and is currently overseeing a caretaker government.

As Iraq Oil Report editor Ben Van Heuvelen noted on Twitter, this fact has already halted the passage of a budget law. And it could give the US grounds to argue that a new government must be ushered in before any Iraqi decision on expulsion could be considered binding, particularly because Iraq’s executive branch ultimately controls foreign troop access to the country.

Also complicating matters was parliament attendance. While the Iraqi parliament voted 170-0 to approve the bill, more than 150 members weren’t in attendance. Factions that grew out of Shia militia organizations arrived to support the expulsion resolution, while many Sunni and Kurdish lawmakers who want the US to remain in the country did not attend the session and did not vote, the New York Times reported. This makes it somewhat more difficult for the government to claim the resolution has clear support.

Despite the uncertainty around the future of foreign troop presence on the ground in Iraq, the resolution alone is nevertheless a strong rebuke of the US’s actions and could mark the beginning of serious changes in the US-Iraq relationship.

Iraq’s vote and Iran’s outrage could have devastating consequences for the region

If the 5,200 American troops stationed in Iraq are forced to leave, it could lead to destabilization in the country and across the region — there is particular concern that a loss of US troops could aid an ISIS resurgence.

Even ahead of Sunday’s vote, the anti-ISIS mission was facing some strain due to Soleimani’s killing. The US’s European allies expressed concern about the safety of their troops in the country, and the US and its NATO allies paused the training of Iraqi forces to fight ISIS. Still, European leaders said the multinational fight against ISIS has to continue.

“Iraq cannot be allowed to sink into chaos, and certainly not under the control of extremists. Therefore, it is important not to let up now in the fight against Islamic State,” said the German defense minister in a statement.

The resolution puts that fight in some jeopardy. Should the government actually mandate the sort of expulsion it outlines, Iraqi security forces will have to continue anti-ISIS initiatives on their own — or in partnership with other powers like Iran, something the US does not want to happen.

In Iran too, officials are contemplating immediate policy changes that could have far-reaching effects.

Soleimani’s killing was a game-changer in a longstanding escalation of tensions between the US and Iran that began with Trump’s withdrawal from the Iran nuclear deal in 2018 and continued with a series of crippling sanctions over the country’s missile program and support for terrorism. Iran met each of these US actions with increasingly bold responses, including attacks on container ships in the Persian Gulf and drone strikes on Saudi oil facilities.

And Sunday, Iranian officials announced a major nuclear policy change. Iran has already begun stockpiling uranium and exceeding enrichment limits imposed by the nuclear agreement; Iranian officials now say the country will no longer abide by any of the commitments outlined in the deal.

Even before Iraq’s vote and Iran’s announcement on its nuclear plans, experts agreed the escalating tensions would cause further instability in the Middle East. Just days after Soleimani was killed, that instability seems all the more certain.