A spate of recent Islamic State-linked terror incidents illustrates the group's resilience and continuing ability to inspire supporters across the globe, as growing branches in certain countries may develop both a greater intent and capability to direct mass casualty attacks in the West in the coming years. Over the past week, authorities worldwide have linked a series of successful attacks and thwarted plots to the Islamic State. On Dec. 14, a father and son pair inspired by the group killed 15 people and injured dozens more at a Hanukkah celebration in Sydney, Australia, the deadliest terror incident in the country's history. The day before, an Islamic State-affiliated gunman killed two U.S. servicemembers and a civilian interpreter in an ambush in Palmyra, Syria. Meanwhile, on Dec. 16, Polish police said they had arrested an individual suspected of planning an Islamic State-inspired attack on a Christmas market, days after German police said they had detained five individuals on similar charges. On Dec. 16-17, Iraqi authorities announced they had arrested multiple suspected Islamic State members, including an alleged senior bombmaker, across the country. And on Dec. 17, Israeli authorities said they had recently detained two people accused of pledging allegiance to the Islamic State and planning to travel abroad to receive training.

• Shortly before the Sydney attack, the gunmen spent nearly a month in the southern Philippines, near where Islamic State fighters retain a small presence. An unnamed senior official, cited by the Australian media outlet ABC, stated that the father and son underwent "military-style training" there. However, Philippine officials have denied this claim, which also lacks publicly available evidence and has not been corroborated by other major media sources.

The Islamic State no longer holds significant territory in the Middle East, but its affiliates elsewhere have grown more powerful, especially in sub-Saharan Africa, and the group's message continues to inspire sympathizers across the globe to plot attacks. The Islamic State's influence peaked in the mid-2010s, when its self-proclaimed caliphate encompassed a vast swath of territory across Iraq and Syria. While its presence in Africa, the Middle East, the Caucasus, South Asia and Southeast Asia was comparatively smaller, it was still substantial in many cases. During this period, the Islamic State was responsible for directing a series of mass casualty attacks (mostly outside of the West, despite some outliers like the November 2015 attacks in Paris), and also inspired scores of sympathizers across Europe, the United States and other Western countries like Australia to commit violence in its name. However, in the late 2010s, a multinational military coalition essentially reclaimed all Islamic State-held territory in Iraq and Syria, while separate operations against the group's other global branches severely curbed its territorial control elsewhere, forcing its fighters to disperse into smaller, weaker insurgencies. Major exceptions, however, have been in sub-Saharan Africa and, to a lesser extent, Afghanistan. In Africa, the group retains significant influence through the Islamic State Sahel Province and Islamic State West Africa Province, which have both been expanding their territorial control, carrying out more frequent attacks and operating farther from their traditional heartlands. And in Afghanistan, the Islamic State Khorasan Province has carried out several mass casualty attacks in the region, and has also been linked to multiple thwarted attacks in Europe and the United States. And although the fall of the Islamic State's caliphate and improved Western counterterrorism capabilities have significantly decreased the frequency and severity of attacks carried out by its followers, the group's propaganda and ideology continue to inspire frequent plots and sporadically successful attacks from lone actors and small cells.

• The Islamic State has exploited anti-Israel and -Western sentiment fueled by the Gaza war to recruit, fundraise and spread its message across the world. African countries where the group is active — including those in the Sahel and the Lake Chad Basin, but also the Democratic Republic of the Congo and Mozambique — have also seen more frequent attacks, as Islamic State fighters capitalize on illicit arms supply chains, weak governance, security vacuums and popular grievances. And though the Islamic State no longer holds major territory in Syria, its remaining fighters there have increased their operations in the past year by exploiting instability following the collapse of Bashar al Assad's regime, a reduced U.S. military presence and the strained resources of Kurdish fighters who have been the main force fighting the group in Syria.
• In addition to the Islamic State's outfits in the Sahel and West Africa — where it also competes with al Qaeda-linked groups — the group has branches centered in the Democratic Republic of the Congo, Mozambique and Somalia. Over the past year, its branch in Somalia has come under intense counterterrorism pressure that has severely constrained its operations, but the group still remains active. The Islamic State branches in the Congo and Mozambique, though less capable than they were a few years ago, have also ramped up the pace of their attacks this year, pointing to their resilience and intent to re-grow their influence.

The main Islamic State threat to Western countries in 2026 will remain the group's ability to inspire and guide local sympathizers to commit attacks largely on their own, but these attacks may become more frequent compared to prior years. Since the collapse of the Islamic State's caliphate in Iraq and Syria in the late 2010s, the main threat posed by the group to the West has stemmed from its ongoing ability to motivate supporters to commit violence — often completely on their own but at times via communication with fighters overseas who give guidance on tactics, targets or other matters. Although a more sophisticated, foreign-directed attack is always possible, there is no reason to believe this threat will overtake that stemming from lone actors and small cells in 2026. Judging from ongoing successes in thwarting many plots, Western counterterrorism capabilities remain much stronger than they were a decade ago, and compared with the mid-2010s, the Islamic State's external operations capabilities are far weaker. This means that Islamic State supporters using readily available weapons like vehicles, bladed weapons or firearms will remain the largest threats, as they are harder for security services to detect and disrupt compared with more complex plots — especially those directed from abroad and/or involving more people using more advanced tactics like using explosives, which leave relatively many more opportunities for interdiction. Still, there are multiple ongoing and potentially intensifying developments that could lead to so-called "inspired attacks" becoming more frequent. For one thing, security services across the West are increasingly prioritizing other threats, opening the door for aspirant attackers to evade detection. U.S. authorities are concentrating more on immigration enforcement, far-left extremism and organized crime; in Europe, authorities are grappling with a surge in Russian sabotage; and elsewhere, like Australia, there has been a greater focus on pro-Palestinian extremism and other threats, like Chinese espionage. Meanwhile, authorities across the West say the average age of Islamic State-linked plotters has been declining while extremists have been increasingly fluid in their ideological beliefs, making it harder for authorities to use traditional detection methods. Furthermore, most Western governments have been cracking down on immigration, ramping up deportations and/or adopting other policies that make their countries more inhospitable for migrants — trends that will continue to fuel Islamic State propaganda and make marginalized individuals more vulnerable to radicalization.

• The many public events surrounding the 2026 Winter Olympics in Italy in February and the World Cup games across Canada, Mexico and the United States in June-July represent high-profile targets for potential Islamic State-linked attacks, despite extensive security preparations.
• As with other threat actors, Islamic State members are experimenting with artificial intelligence tools, primarily for propaganda purposes. These AI tools are making it easier for the group to create, disseminate and, perhaps most crucially, translate content to reach larger audiences using fewer resources. The group and its Western supporters are also exploring other emerging technologies to advance their activities. These include cryptocurrencies to more covertly transfer funds; commercially available drones for reconnaissance, propaganda creation and, in some cases, delivering improvised explosives; 3D printing to create weapon components; and smart devices, which the perpetrator of the New Year's Day 2025 vehicle ramming in New Orleans used to conduct pre-attack surveillance.

In the coming years, some of the Islamic State's branches — including in sub-Saharan Africa, Syria and Afghanistan — may also become both more willing and able to direct mass casualty attacks in the West as they expand. Developing an external operations apparatus that can successfully oversee a mass casualty attack in the West — involving the use of multiple perpetrators, complex tactics and/or sophisticated weapons — requires significant resources and motivation. During the Islamic State's heyday in Iraq and Syria in the mid-2010s, its core group there had both, but no single branch has since demonstrated sufficient intent and capability to replicate the group's past success. However, unlike a decade ago, the Islamic State is now more decentralized, connected by a General Directorate of Provinces that coordinates among its globally dispersed branches. Thus, while there is no extremely strong core, numerous smaller Islamic State affiliates around the world could pose future threats. Those in the Sahel and West Africa — which are expanding their territorial control, fighters and material capabilities — are among the most likely to develop the intent and capability to direct larger attacks against the West. For now, these African fighters remain focused on conducting attacks in their immediate regions, though the Sahelian branch has been linked to plots elsewhere in Africa, suggesting growing aspirations that could one day include the West — especially Europe, given its geographic proximity and transcontinental migrant flows. In Syria, though the Islamic State is far smaller and weaker than a decade ago, its remaining fighters have already shown a clear intent to direct attacks against the West and, on the ground, are already exploiting a more permissive environment to try to reorganize. This effort could become easier in the future if Syria's fragile political transition descends into greater government instability, economic hardship and/or security vacuums, especially if thousands of Islamic State fighters are freed from increasingly insecure Kurdish-operated prisons. But of all its global branches, the Islamic State's affiliate in Afghanistan is by far the one linked to the most Western attack plots in recent years, indicating an already strong intent. Should the group's capabilities grow to match — for example, if it intensifies recruiting among Central Asian diaspora communities and directs attackers toward the West, or if the Afghan Taliban's recurring clashes with Pakistan divert resources away from efforts to combat the group — the risk of a successful, large-scale attack in the West, which has so far been prevented, will increase.

• Even if Islamic State branches continue to face constraints on their abilities to direct mass casualty attacks in the West, they will become comparatively more capable of kidnapping foreigners and attacking Western targets (e.g., industrial sites, hotels, entertainment venues and diplomatic outposts) in areas closer to where they operate. 
• Given the cross-branch coordination enabled by the Islamic State's General Directorate of Provinces, it is also possible that other branches could work together to overcome their individual constraints in directing a larger attack in the West. Over the past two years, the group's branches in Iraq, Pakistan, Somalia and Yemen have all been linked to attacks beyond their immediate region.
• Separate from the Islamic State, al Qaeda still aspires to attack the West as well. Years of strong counterterrorism pressure across its historical strongholds in the Middle East and South Asia have heavily weakened the group. However, al Qaeda's franchises in sub-Saharan Africa — including Jama'at Nusrat al-Islam wal-Muslimin (JNIM) across the Sahel and West Africa, as well as al Shabaab in Somalia — are becoming more powerful as they encroach closer to capital cities in their respective areas of operation. Compared with JNIM, al-Shabaab likely has stronger external operations ambitions, given its history of conducting attacks against regional Western targets and its involvement in a few plots in Western countries themselves. Elsewhere, al Qaeda in the Arabian Peninsula (AQAP) has historically plotted the most attacks in the West. While AQAP is far weaker than it was in the first two decades of the century, it retains a presence in Yemen, where ongoing territorial shifts could create security vacuums for the group to exploit.