Commentary Marking the 25th Anniversary of the 9/11 Attacks
Date of publication: September 7, 2026
On 8 September 2026, Filip Sommer, Director of the Prague Center for Middle East Relations (PCMR) at CEVRO University, commented on how the terrorist attacks of 11 September 2001 transformed the global security environment. The attacks were carried out by al-Qaeda against targets in the United States, including the World Trade Center towers and the US Department of Defense.
You can read the full commentary here.
Context
The 9/11 attacks fundamentally changed the way Western states understood security. Until then, attention had focused primarily on threats posed by other states. After 2001, however, non-state actors, terrorist networks, and the risk that a relatively small organization could carry out an attack with strategic consequences moved to the center of security policy. The first-ever invocation of Article 5 of the North Atlantic Treaty symbolized this shift.
This was followed by an extensive restructuring of intelligence and security institutions, significantly more intensive international information sharing, closer monitoring of terrorist financing, tighter aviation security, and expanded surveillance powers. These measures made it substantially more difficult to prepare complex attacks comparable to those of 9/11. At the same time, however, they opened a lasting debate about where to draw the line between security, privacy, and civil liberties.
Another important legacy has been the expanded use of military force against non-state actors beyond traditional battlefields, including through special operations forces such as Delta Force and the Navy SEALs, unmanned aerial vehicles, and targeted strikes. The War on Terror also contributed to the normalization of preventive military interventions and extraordinary security measures. The consequences of 9/11 have therefore not been limited to the security sphere. They also include enormous financial costs, the long-term militarization of foreign policy, the forced displacement of millions of people, and a degree of fatigue within Western societies over large-scale foreign interventions. This fatigue now also affects the willingness of the United States and its allies to become involved in further conflicts, particularly in the Middle East, including the current war involving the United States, Israel, and Iran.
The impact was profound. In connection with the fight against terrorism, the United States substantially expanded its military and security engagement in the Middle East and the wider region, particularly in Afghanistan. This did not mark the beginning of the American presence in the region, but it fundamentally changed its scale, character, and declared objectives. Afghanistan and Iraq must nevertheless be clearly distinguished, because the two interventions were undertaken for different reasons. The intervention in Afghanistan was a direct response to 9/11: the Taliban regime had provided sanctuary to al-Qaeda, which planned the attacks. The initially relatively limited objective of dismantling al-Qaeda and removing the regime that protected it gradually developed into an extensive state-building project. The Taliban’s return to power in 2021 demonstrated that military superiority and enormous financial resources do not, in themselves, guarantee the emergence of legitimate and viable institutions or a functioning state.
The 2003 invasion of Iraq, by contrast, was based on false and unsubstantiated claims used by the Bush administration to justify the intervention. These concerned, above all, Iraq’s alleged stockpiles and renewed production of weapons of mass destruction, as well as purported cooperation between Saddam Hussein’s regime and al-Qaeda. The central claims regarding weapons programs and stockpiles were not substantiated, nor was any operational cooperation between the Iraqi regime and al-Qaeda demonstrated. Saddam Hussein played no role in the 9/11 attacks. The invasion of Iraq therefore cannot be presented as an equally well-founded response to the same threat, even though the US administration placed it within the broader framework of the War on Terror.
The invasion of Iraq profoundly reshaped the regional balance of power. The dissolution of the Iraqi army, extensive de-Ba’athification, and the subsequent consolidation of a political system based on ethnosectarian power-sharing contributed to the weakening of the state, the emergence of an insurgency, and sectarian violence. Al-Qaeda in Iraq gained prominence within this environment and subsequently evolved into the Islamic State, also known as the Islamic State of Iraq and the Levant or the Islamic State of Iraq and Syria. Its later rise was also facilitated by the Syrian civil war and the collapse of state control over parts of Syrian territory.
The removal of Saddam Hussein’s regime also strengthened Iran’s regional position and opened political space for its Iraqi allies, many of whom had taken refuge in Iran during Saddam’s rule. The long-term legacies of the invasion include the empowerment of armed non-state actors, the erosion of the state’s monopoly on violence, and distrust among parts of the Sunni population toward the new political order.
It would nevertheless be incorrect to trace every contemporary conflict in the Middle East back to 9/11 or the subsequent American interventions. The Arab uprisings, the Israeli–Palestinian conflict, and competition among regional powers have their own, often much older, causes. The War on Terror did, however, significantly reshape the environment in which these conflicts have unfolded. It not only failed to resolve certain security problems but also contributed to their further aggravation.
The outcome depends on how we define the objectives of counterterrorism. Counterterrorism is inherently a never-ending process rather than a war that can be concluded through a single decisive victory. Terrorism is a method of political violence: a particular organization can be dismantled, but this does not prevent other actors from adopting the same method.
In assessing the past 25 years, I believe that two perspectives are particularly important. The first is a critical one: the way in which counterterrorism is conducted can paradoxically fuel terrorism itself. Civilian casualties, arbitrary detention, torture, and support for repressive regimes create grievances that extremist organizations exploit to justify violence and recruit new members. This does not mean that every military intervention automatically produces more terrorism. A poorly conducted operation can, however, deliver short-term military gains while strengthening, over the longer term, the environment from which terrorist groups draw support. Their ideological framework can survive even after they lose territory or a particular organization is defeated.
The second perspective concerns genuine operational successes. Targeting and disrupting the senior and mid-level leadership of terrorist organizations—often referred to as leadership decapitation—can be an effective means of limiting their operational capacity and influence. This involves more than eliminating a prominent leader. The loss of experienced commanders, organizers, and intermediaries can disrupt attack planning, financing, the transfer of expertise, and coordination among individual cells. Mid-level leaders, in particular, often connect strategic decision-making with an organization’s day-to-day operations.
The effect, however, is neither automatic nor necessarily permanent. Organizations with a sufficiently broad membership base, established succession mechanisms, and local support may be able to replace lost leaders. Leadership decapitation can therefore significantly reduce their operational capabilities, but it does not in itself eliminate their ideology, political ambitions, or sources of support. It should not be confused with complete strategic defeat.
Significant achievements include the weakening of al-Qaeda’s original leadership, the territorial defeat of the Islamic State’s self-proclaimed caliphate, and the disruption of Hizballah’s internal structure. Yet the threat has not disappeared: it has evolved, become more decentralized, and, in some regions, shifted toward powerful local affiliates. The capacity to prevent attacks is now substantially greater than it was before 9/11, whereas the ability to address the underlying conditions that allow terrorist organizations to replenish their ranks remains much weaker. In my view, the central contradiction of counterterrorism to date lies precisely in the gap between these two dimensions.
Today’s terrorist threat is considerably more decentralized and multilayered. In 2001, al-Qaeda was a relatively hierarchical organization capable of preparing a complex attack over an extended period from a secure foreign sanctuary. Contemporary organizations more often operate as networks of regional affiliates that share a common brand and broad ideology but have their own leadership, financing, and local objectives.
For people living in conflict-affected areas, these regional organizations represent the most serious threat. They include, for example, the al-Qaeda-affiliated Jama’at Nusrat al-Islam wal-Muslimin in the Sahel, al-Shabaab in Somalia, Islamic State–Khorasan Province in Afghanistan, and several African branches of the Islamic State. Their strength does not derive solely from their capacity to carry out terrorist attacks. Some of them control territory, collect taxes, provide limited services, and seek to replace or compete with the state.
I would also highlight the cooperation between certain al-Qaeda affiliates—specifically al-Qaeda in the Arabian Peninsula—and other organizations such as Yemen’s Houthis. Such cooperation cuts across the conventional sectarian divide between Sunni al-Qaeda and the Shi’a Houthis and demonstrates the pragmatism of these groups when coordinating action against a common enemy, such as the West.
For Europe and the United States, by contrast, the more immediate threat comes from the radicalization of individuals or very small cells. The internet, social media, and encrypted communications enable organizations to reach sympathizers without establishing direct organizational contact with them. This can produce less sophisticated but harder-to-predict attacks by individuals inspired by the propaganda of the Islamic State, al-Qaeda, or other extremist movements. The 2026 US threat assessment likewise identifies homegrown lone actors as the most likely perpetrators of a terrorist attack on US soil.
It is therefore impossible to identify a single most dangerous actor irrespective of geographical context. In conflict-affected regions, the main threat comes from regional affiliates capable of combining terrorism with insurgent warfare and territorial governance. At the same time, there has recently been considerable pressure to curtail the activities of armed non-state actors, including Hizballah in Lebanon, pro-Iranian militias in Iraq, and the Kurdistan Workers’ Party in Türkiye, as well as the Kurdish militias associated with it in Syria under the umbrella of the Syrian Democratic Forces.
In Western countries, decentralized radicalization among individuals is the more likely threat. Major brands such as al-Qaeda and the Islamic State nevertheless remain important because they connect these two levels: they provide ideology, propaganda, expertise, and international prestige to both local organizations and self-directed perpetrators.