To defeat the Islamic State as an underground insurgency, someone must develop good governance in its former territories in Iraq and Syria, convincing locals to help uproot the group—an unlikely feat for which there are no credible volunteers. Unlike its previous revival, the Islamic State now has two countries where it can exploit problems, as opposed to just Iraq in the past.

The Islamic State will probably further regionalize the conflict and seek opportunities beyond Iraq and Syria. Already the group regards Iraq and Syria as one theater, shifting assets between the two countries depending on its perceived dangers and opportunities. The group also maintains an extensive network in Turkey, and has attacked Jordan, Lebanon and Saudi Arabia, among other countries. The Islamic State will probe these areas for weaknesses, using its operatives and local supporters to conduct attacks and develop an enduring presence.

Most troubling for the long term, the Islamic State has nurtured the flame of jihad around the world. Even as the group declines, the ideas it champions—the necessity of a caliphate, the glory of brutality and the evil of Western states—have spread further, as the staggering volume of foreign fighters suggests. The Islamic State’s propaganda is extensive and almost ubiquitous. It, or would-be successor organizations, will try to harvest the ideas that the early Islamic State leaders planted.

The Islamic State will likely continue, and may even focus on, terrorist attacks in the West. In 2015, Paris suffered the worst terrorist attack on French soil in history when Islamic State gunmen and suicide bombers killed 130 people. France and other European states saw smaller attacks that year and the next, and by October 2017, five attacks linked to or inspired by the Islamic State targeted the United Kingdom—its most lethal year in terrorism since 2005. These high-profile attacks allow the Islamic State to maintain relevance to would-be and current supporters, convincing them to fight for the group despite its setbacks in Iraq and Syria. The attacks also signify revenge for the group’s tremendous losses. Although U.S. efforts to destroy the Islamic State’s havens hinder the group’s ability to carry out sophisticated attacks, some attacks involve an Islamic State facilitator who helps recruit or directs the attacker, but does not provide elaborate operational support. Many of these attacks are low-tech but quite bloody: the Bastille Day attacker in Nice in 2016, for example, killed eighty-six people by driving a truck through a crowd.

Internal dynamics make Europe a particularly likely target, and in the short term the terrorism threat may grow as the caliphate collapses. The Syrian conflict has attracted over six thousand European volunteers. Some of these European foreign fighters will die and some will stay in the war zone, but some will also likely return to their home countries. One EU official estimates that approximately 1,500 will return. A fraction of those who return home may commit terrorist attacks or recruit locals to join the cause. The potential size of that fraction is unclear, but even a small percentage out of 1,500 can frustrate local police and security services. Europe contains more radicalized Muslims relative to their overall population, as suggested by the dramatically higher number of foreign fighters from European states. In addition, many European Muslims integrate poorly into their broader communities, which discourages them from cooperating with local intelligence and law-enforcement services. Finally, European intelligence services vary in skill: some, including those of France and the United Kingdom, are highly skilled, while others, such as Belgium’s, are under-resourced and less capable of responding to terrorism threats. Fortunately, with heavy U.S. prodding and support, European states have improved intelligence cooperation and otherwise tightened their defenses. But this will remain a long-term challenge.

IN COMPARISON with Europe, the Islamic State poses a more manageable threat to the U.S. homeland. Since the September 11 attacks, ninety-seven Americans have died in jihadist-related attacks in the United States (the figure was ninety-five until the October 2017 truck-ramming attack in New York City, which killed two Americans and six foreign visitors). The two deadliest attacks, in San Bernardino in 2015 and in Orlando in 2016, that together killed sixty-three Americans, involved individuals who claimed some allegiance to the Islamic State but acted independently of the group—often referred to as “lone wolves.” Although any death from terrorism is deplorable, the number of American deaths in the U.S. homeland—ninety-seven—is far lower than many experts, both inside and outside of government, predicted.

Multiple factors likely explain this relatively low level of violence. First, senior U.S. officials overestimated the number of radicals in the United States after 9/11 when they spoke of thousands of jihadist terrorists in the United States. Second, the American Muslim community regularly works with law enforcement, leading to many arrests. As former FBI director James Comey explained,

“They do not want people committing violence, either in their community or in the name of their faith, and so some of our most productive relationships are with people who see things and tell us things who happen to be Muslim.”

“Lone wolf” attacks will likely continue. The trend towards “lone wolf” attacks has grown: although the absolute number of attacks remains low, the scholar Ramon Spaaij found that the number of “lone wolf” attacks since the 1970s grew by nearly 50 percent in the United States and by more than 400 percent in the other countries he surveyed. The Internet and social media explain part of this increase, as both aid the Islamic State in inspiring individuals to act in its name. The October 2017 attack in New York was lifted straight out of the Islamic State’s propaganda organ Rumiyah, which called for using vehicles to mow down pedestrians and then for the attacker to exit and continue to attack. Would-be fighters who do not travel pose a danger as well: according to one 2015 study of the terrorist plots in the United States, 28 percent of returned foreign fighters participated in a plot, but a staggering 60 percent of those who considered but did not attempt to travel became involved in a terrorist plot. As travel to Iraq and Syria loses its luster or becomes infeasible, frustrated jihadists might attack at home. As one French jihadist told the scholar Amarnath Amarasingam, “We believe that even a small attack in dar ul-kufr [the land of disbelief] is better than a big attack in Syria. As the door of hijrah [going to the Islamic State] closes, the door of jihad opens.” Over time this frustration will decline, as would-be fighters no longer have firsthand contact with friends or family who went to fight, but the short-term danger is quite real.

Although the Orlando attack suggests that “lone wolf” attacks can be bloody, most “lone wolves” are incompetent; they are unlikely to succeed compared to trained foreign fighters who return to their home countries. But “lone wolves” have a strategic impact by altering politics in the United States and Europe, thus shattering the relations between Muslim and non-Muslim communities that are so vital to counterterrorism and to democracy itself. “Lone wolf” attacks increase Islamophobia in the West. After the attacks in Paris and San Bernardino, concerns about terrorism spiked. In the weeks following the Paris attacks in November 2015, London’s Metropolitan Police Service announced that attacks targeting Muslims had tripled. Meanwhile, in the United States, assaults against Muslims have increased to nearly 9/11-era levels.

This Islamophobia can also begin a dangerous spiral. As communities become suspect, they withdraw into themselves and become less trustful of law enforcement, which results in providing fewer tips. In contrast, if a community has good relations with the police and society, fewer grievances exist for terrorists to exploit and the community is more likely to point out malefactors in their midst. Even though he was never arrested, the attacker in Orlando came to the FBI’s attention because a local Muslim was concerned by his behavior and reported him.

Such problems risk fundamental changes in politics and undermine liberal democracy. Far-right movements are growing stronger in several European countries. In the United States, Islamophobia and fears of terrorism—despite the less-than-anticipated number of attacks on U.S. soil since the 9/11 attacks—have fueled the rise of anti-immigrant politics.

THE TRUMP administration continued the Obama administration’s military campaign against Islamic State forces in Iraq and Syria, and has loosened restrictions on military commanders and deployed additional forces to Syria—nearly doubling the number of previously deployed forces in the fight for Raqqa. Additionally, the administration has maintained the coalition of states and local actors that the previous administration cobbled together. Furthermore, the aggressive global intelligence campaign begun under President George W. Bush and continued under Obama remains robust. Taken together, such efforts have hindered Islamic State operations and steadily forced it underground.

In his first year in office, however, the president has taken several steps that may impede the struggle against jihadist terrorism. First, in his campaign rhetoric and through actions like Executive Order 13769 (the so-called “Muslim ban”), the Trump administration demonized American Muslims and damaged relations between religious communities—a traditional source of American strength, pride and values. Such actions increase the allure of the Islamic State and other groups claiming that the West is at war with Islam, while also adding credibility and legitimacy to their ideas. In addition, these actions increase the likelihood that Muslim communities will fear the police, the FBI and other government institutions, and thus be less likely to cooperate with them. This enables “lone wolves” to remain undetected and offers fodder for Islamic State virtual recruiters trying to convince Muslims that the West is the enemy.