Threats from terrorist groups such as ISIS are again surging across the globe three years after the U.S. withdrew from Afghanistan, an exit that marked a new phase in the war on terrorism.
ISIS has claimed responsibility for several deadly attacks this year across the world, from Turkey to Iran and Russia. ISIS-affiliated actors also carried out a stabbing attack in Germany this month and threatened a Taylor Swift concert in Austria.
The renewed ISIS threat, along with the proliferation of terrorist groups across the Middle East, Central Asia and African Sahel regions, underscores how the U.S. and its allies are struggling to combat these groups in an era that is also marked by threats from state actors, including Russia, Iran, North Korea and China.
Still, in Washington and among the broader American public, there is no appetite for long-term foreign invasion missions to combat terrorism on the heels of the 20-year war in Afghanistan or the eight-year war in Iraq.
Instead, a smaller number of U.S. troops are deployed in countries willing to host an American presence, ostensibly giving the U.S. an “over-the-horizon” view on threats. But that has proven a difficult strategy to manage, with Iraq looking to possibly expel U.S. forces and African nations giving Americans and Europeans the boot after falling to military coups.
While not at the height it was before, the terrorism threat is again growing, and security experts worry the U.S. is falling back into a reactive posture.
“It takes one bomb going off in Times Square,” said Colin Clarke, nonresident senior fellow at the Foreign Policy Research Institute. “We’re just far too reactive in our policy, and we’re not proactive enough.
“We haven’t learned a lot, sadly, I think, from 9/11. We need to prepare for these things and prepare our responses. We’ve got to be clinical. We’ve got to be kind of judicious in how we respond to these issues,” he added.
The U.S. completed its withdrawal from Afghanistan three years ago Friday in a chaotic retreat that left 13 American service members dead from an ISIS-K suicide bombing at the Kabul airport that also killed some 170 Afghan civilians.
American forces have largely defeated ISIS since the group rose to power in 2014 and took vast swaths of Syria and Iraq. The U.S. and an allied coalition force diminished the group by 2017 and forced it out of the territory it once held.
Yet the U.S. has continued to combat a resilient ISIS. There are some 900 troops in Syria and roughly 2,500 in Iraq. The Iraqi government invited the U.S. to the country to help defeat ISIS in 2014, and the deployment there also allows American forces to remain in neighboring Syria.
In the past three years, ISIS-K, the group’s Central Asia branch, has rebounded. It claimed responsibility for January attacks in Kerman, Iran, that killed nearly 100 people; a shooting at a Moscow concert hall in March that killed more than 130; and a shooting at a church in Istanbul that killed one, also in January.
The broader ISIS network has claimed responsibility for a knife attack in Germany this month that killed three people and was behind a foiled plot to kill thousands of people at Swift’s concert in Austria, according to authorities.
U.S. Central Command said in a July statement that ISIS was responsible for 153 attacks in Iraq and Syria in the first half of 2024 and was “on pace to more than double the total number of attacks” it claimed last year.
The U.S. warned ISIS was trying to reconstitute even as American forces hunt down the roughly 2,500 ISIS members at large in Iraq and Syria.
ISIS-K also remains a regional hub, funneling “hundreds of thousands of dollars to financial facilitators as well as providing personnel and weapons to support external operations,” the Treasury Department said in a report this year.
Pentagon press secretary Maj. Gen. Patrick Ryder told reporters this week the U.S. was “laser-focused” on combating terrorism and was enhancing cooperation with allies to share intelligence and information to foil plots.
“We know that we can’t turn a blind eye to the threats from organizations such as ISIS-K,” he said. “We have and continue to invest in and deploy modern capabilities to keep Americans safe.”
Vladimir Voronkov, under secretary-general of the United Nations Office of Counter-Terrorism, warned in a briefing this month that ISIS “has improved its financial and logistical capabilities in the past six months, including by tapping into Afghan and Central Asian diasporas for support” and has also increased its recruitment drive.
“Sustained counter-terrorism efforts will be required to prevent [ISIS] from building upon these gains,” he said. “We must unite to prevent Afghanistan from once again becoming a hotbed of terrorism.”
The renewed threat extends far beyond ISIS. Deaths from terrorism across the world increased by 22 percent in 2023 to 8,352, the highest level since 2017, according to the Institute for Economics and Peace’s latest global terrorism index.
While there was a decrease in the number of incidents, the rise in deaths shows terrorism is becoming “more concentrated and more lethal” the report said.
The Middle East remains a crucial region for counterterrorism efforts, but the future of the U.S. deployment there remains uncertain.
Baghdad is in high-level talks to potentially force the U.S. out of Iraq. Iraqi officials have raised concerns about repeated clashes in their country between the U.S. and Iranian-backed groups.
If the U.S. were to leave Iraq, it would likely have to exit Syria, too, considering America’s technical basis to be there is to protect Iraqi territory.
Iraqi forces have trained with the U.S. to counter ISIS and other violent extremists, but an American withdrawal could lead to an ISIS resurgence, said Aaron Zelin, senior research fellow at The Washington Institute for Near East Policy.
Zelin said if ISIS takes over parts of northeastern Syria when the U.S. leaves, it will “get more money, fighters [and] weapons” and restart an insurgency in Iraq.
“As long as the U.S. remains in Iraq and Syria, they should manage the issue, more or less,” he said. “Obviously, it would change if the U.S. left.”
But the most dangerous hotbed for terrorism is in Africa’s Sahel region, making up the western and north-central parts of the continent.
In Africa, ISIS has a presence, but al Qaeda-linked groups pose the most difficulty. Jamaat Nusrat Al-Islam wal Muslimeen is the most persistent threat across the Sahel, while Al-Shabaab has long plagued Somalia and East Africa.
Burkina Faso remains the most terrorist-ridden country in the world, making up a quarter of all terrorism-related deaths, according to the global index report.
Sahel countries have long struggled to combat violent extremist groups, and some of them face greater instability after falling to military coups, including Niger, Mali and Burkina Faso.
The military juntas in power have forced out American and French troops. In August, the U.S. completed a withdrawal from its bases in Niger after the military seized power in 2023, endangering counterterrorism efforts by removing American forces from an important regional foothold. France, a major counterterrorism partner, has also been forced out of Mali, Niger and Burkina Faso.
Across Africa, terrorism-related fatalities increased 56 percent between 2021 and 2024, according to the Africa Center for Strategic Studies at the Pentagon-funded National Defense University. The Sahel made up around half of those deaths, and the region has seen a tripling in terrorism killings.
Joseph Siegle, director of research at the Africa Center for Strategic Studies, said the “dramatic increase” in violent incidents across Africa is worrying. He said the threat is complex, pointing to multiple violent militant groups behind the surge actively recruiting from a struggling low-income population with grievances against the government, especially those run by military juntas.
“We are facing these established insurgencies now, rather than one-off terrorist acts,” he said. “They require whole of society efforts to combat them. It requires having a government presence on the ground that can provide services and can counter these arguments that governments don’t care.”
The U.S. has been combating terrorism since 9/11, and Americans are tired of large-scale deployments such as those in Iraq and Afghanistan. But counterterrorism experts say it’s important to maintain at least a small and robust intelligence and force network abroad to reduce the ability for violent groups to carry out attacks.
After Afghanistan, the U.S. pivoted to larger threats, focusing on the war in Ukraine and managing the threat from Russia while supporting Israel against Iran. China remains the topmost national security concern in Washington.
Still, worldwide threats are not isolated events. In Africa, Russia has been moving into countries such as Niger, taking advantage of nations held by military juntas to exploit resources for protection and military training.
That brings a geopolitical dynamic to the counterterrorism fight, said Jason Blazakis, director of a center on terrorism at the Middlebury Institute of International Studies.
“There’s an element where this plays into the broader state actor threat as well, because we’re ceding the ground … to countries like Russia,” he said.
“Some of these are also tightly connected, especially when it comes to great power competition. And great power competition quite often will devolve into the use of proxies. So we should also prepare for that possibility in the years ahead.”