Many Americans, including leaders not normally critical of the president, worried that a U.S. withdrawal would give the Islamic State a chance to rise again. For instance, former secretary of defense Jim Mattis warned, “If we don’t keep the pressure on, then ISIS will resurge.”
Trump tried to placate some critics by allowing a remnant of U.S. forces to remain in Syria, ostensibly to protect Kurdish-held oil. Then the United States struck a blow against ISIS when Special Operations forces killed its leader, Abu Bakr al-Baghdadi — eliminating a key leader at a critical time.
The Islamic State may make modest gains with the United States gone — but as the Baghdadi raid reveals, the U.S.-led counterterrorism campaign will not end and a full comeback is unlikely. I’ll explain below.
It’s important to remember how the Islamic State rose and fell
Al-Qaeda in Iraq, which went through a series of names before proclaiming itself the Islamic State, emerged to fill the void after the 2003 U.S. invasion of Iraq toppled Saddam Hussein without planning for the aftermath. The disastrous occupation led to a brutal civil war. But by 2008, Michael Hayden, then CIA director, declared that al-Qaeda in Iraq was “near strategic defeat.”
The facts supported his claim. The organization had lost its territory and was launching far fewer attacks; its leadership was devastated; and former supporters were criticizing it for its killing of Muslim civilians. By 2011, when the United States withdrew its forces, al-Qaeda in Iraq was on the ropes.
So what happened? How, by 2014, were the Islamist militants able to return and proclaim a caliphate in Iraq and Syria, ruling over a territory the size of Britain?
First, when the United States withdrew, then-Iraqi Prime Minister Nouri al-Maliki and his predominantly Shiite government were supposedly committed to cooperation with the country’s Sunni Muslim community. Instead, Maliki’s regime began to arrest Sunnis who had fought the Islamist militants and began “attacking, intimidating, [and] marginalizing” Sunni representatives, as one Iraqi former minister put it. This enabled the Islamic State to claim that it was the champion of Sunni Muslims in a sectarian struggle. Further, to fill its ranks, ISIS launched a series of prison breaks that freed hardened Islamist militants.
Meanwhile, Syria collapsed into civil war — a war that began as an uprising against the authoritarian Bashar al-Assad regime but quickly became a sectarian conflict. Syria’s chaos gave Islamist militants a potent recruiting call and a place to organize and regroup. The Islamic State exploited social media, using Twitter and Facebook to reach millions of Muslims around the world.
The Islamic State’s caliphate, however, proved short-lived. In 2014, Washington gathered a coalition of Western allies, regional states and local militias that steadily shrank the Islamic State’s territory; by 2019, ISIS was forced underground.
The U.S. withdrawal from Syria will give the Islamic State some advantages
The Islamic State was already in a better situation before the latest U.S. withdrawal than it was when the United States left Iraq in 2011. It has far more fighters under arms and conducted more frequent attacks than it did eight years ago.
To be clear, the U.S. decision to withdraw most of its forces from Syria is good news for the Islamic State. The Kurdish-dominated SDF will probably concentrate on fighting Turkey, not the Islamic State’s remnants — leaving the Islamic State facing far less pressure from its former top local enemy.
Once again, the Islamic State has launched prison breaks, though it’s not yet clear how many fighters it has freed. The United States will have a more difficult time collecting intelligence, both because the SDF won’t be collecting as much information and because the United States will have a harder time flying surveillance aircraft and conducting airstrikes now that Russia, Syria and Turkey control the territory and could try to shoot down U.S. aircraft.
But other factors are likely to lower the risk from the Islamic State
However, the Islamic State doesn't have some of the advantages it did in 2011. The Iraqi regime is treating Sunni Muslims far better, and its military and intelligence services are more competent and aggressive. Moreover, Iraqi Sunnis who lived under the former caliphate are not eager for ISIS to return.
Nor is the Islamic State likely to have as much freedom in Syria as it had before. Turkey — which once allowed Islamist fighters to travel through its territory — has been attacked by ISIS and is fighting instead of tolerating the militants. European countries have gotten better at preventing terrorist attacks. Russia and Syria, now working with the SDF, oppose the Islamic State. Meanwhile, the U.S. raid on Baghdadi suggests that the United States and its allies will continue to try to kill Islamic State leaders in Iraq and Syria. Although these strikes may not destroy the group, they can worsen leadership struggles and force it to hide rather than plot attacks.
Meanwhile, social media platforms have become far more aggressive in removing ISIS propaganda and recruiting accounts and blocking Islamist militant content. The U.S. government has become more tech-savvy as well, monitoring suspected terrorists who used these platforms. A 2018 University of Maryland report found that terrorists who abstained from social media were more likely to succeed than those who used it.
The United States still has more than 5,000 troops nearby in Iraq, focused on fighting the Islamic State, and they will also gather intelligence and conduct raids in Syria.
Of course, we don’t yet know what else might happen. History tells us not to rule the Islamic State out. But neither should we be quick to assume it will make a full comeback.
Daniel Byman (@dbyman) is a professor in the School of Foreign Service at Georgetown University and a senior fellow at the Brookings Institution. This essay draws on his new book, “Road Warriors: Foreign Fighters in the Armies of Jihad."