On the 23rd anniversary of the September 11, 2001, terrorist attacks, Americans continue to debate the extent of the threat terrorism poses to the country. In response to the attacks, the United States (U.S.) declared a war on terrorism, which led to invasions of Afghanistan and Iraq. The U.S. government has spent billions of dollars on counterterrorism efforts to prevent another attack like September 11. These measures have been effective, as there have been no significant attacks on U.S. soil since then.
A Washington Post poll tracked American perceptions of security threats in ten-year intervals since 2001. In 2002, 55 percent of respondents felt that the country had become safer since September 11. This percentage declined to 42 percent in 2011 and 33 percent in 2021. Additionally, the proportion of Americans who believed the U.S. was safer from terrorism compared to the period before September 11 dropped from 64 percent in 2011 to 49 percent in 2021. What might the results be if the poll were conducted in 2024? This article, using the Global Terrorism and Trends Analysis Center (GTTAC) Records of Incidents Database (GRID), aims to explore this question by examining three types of terrorism: domestic terrorism, international terrorism, and state-sponsored terrorism.
Domestic Terrorism
Americans are increasingly concerned about domestic terrorism, mainly home-grown extremism and far-right extremism. Home-grown extremism involves American-born Muslim individuals who become radicalized through social media. Unlike European Union countries, the U.S. has rarely seen attacks from these individuals. However, the situation has worsened following the Hamas terror attacks on October 7. The killing of 1,200 Israeli civilians by Hamas has led the Israeli government to respond aggressively. In retaliation, Israeli actions have resulted in over 40,000 Palestinian deaths in Gaza, including many civilians and a small number of Hamas militants. The high civilian toll has caused significant trauma in Muslim countries and deeply affected U.S. universities, where it has become a divisive issue among students. Western governments are concerned about the potential consequences of the ongoing violence and the political debates surrounding the Israeli-Palestinian conflict, which may lead to increased radicalization on social media platforms.
More importantly, Americans are increasingly concerned about domestic far-right groups. Although attacks by these extremist groups are infrequently recorded in terrorism databases due to differing methodologies and criteria for including terrorism-related incidents, their impact is deeply troubling. For example, on January 6, 2021, the U.S. Capitol was violently breached by a mob of demonstrators, many of whom were affiliated with anti-government militia groups and far-right extremists. The attack aimed to disrupt the certification of the 2020 presidential election results and was marked by a coordinated effort from various extremist factions, including the Oath Keepers, Three Percenters, and Proud Boys. The raid on the Capitol was widely condemned as an act of domestic terrorism, highlighting the dangerous potential of anti-government militias fueled by far-right rhetoric.
Additionally, these extremists can appear suddenly and commit mass violence. For example, on May 14, 2022, a tragic mass shooting occurred in Buffalo, New York, when an 18-year-old gunman, Payton Gendron, opened fire at a grocery store, killing ten people and injuring several others. Motivated by extremist far-right ideology and influenced by racist conspiracy theories, Gendron believed in the so-called “great replacement theory,” which falsely claims that immigration undermines the white population. This attack highlighted the severe consequences of extremist ideologies and the urgent need to address radicalization and hate-driven violence. Today, far-right extremist groups remain active and are capable of carrying out attacks. They are also increasingly networked globally, which enhances their potential for violence.
International Terrorism
International terrorism also seems increasingly threatening today. While U.S. counterterrorism efforts have successfully prevented jihadist attacks by ISIS and Al Qaeda on American soil, both groups continue to commit violent acts globally. Their affiliates have expanded operational reach to Asia, Africa, and the Middle East. In Asia, these groups are active in regions such as Afghanistan, Pakistan, and the Philippines. In Africa, rising grievances, economic instability, and the spread of radical Salafi-jihadist ideologies, particularly in countries experiencing military coups like Mali and Burkina Faso, have created more opportunities for these terrorist organizations. In the Middle East, they are responsible for hundreds of attacks each year in Syria, Iraq, and Yemen.
From 2018 to 2022, ISIS and its affiliates significantly increased their attacks, as shown in Figure 1 below. The frequency of these attacks steadily rose during this time.
ISIS’s affiliates remain significant threats in their operational regions, as illustrated in Figure 2 below. From 2018 to 2022, ISIS-Core, based in Syria and Iraq, was responsible for 2,885 attacks. Meanwhile, its affiliate in the Democratic Republic of Congo, ISIS-DRC, conducted 1,050 attacks. Emerging from the Allied Defense Forces (ADF), ISIS-DRC has continued its violent activities into 2023 and 2024, making it one of the most active ISIS affiliates. ISIS-West Africa, headquartered in Nigeria and extending its reach to Cameroon and Niger, has competed with Boko Haram and targeted Christians in its attacks. ISIS-Mozambique, another active affiliate, is notorious for its beheadings in northern Cabo Delgado and remains operational in 2024.
ISIS-Khorasan (ISIS-K) is particularly concerning, especially after the Taliban’s takeover created a power vacuum that ISIS-K has exploited. The ongoing grievances under Taliban rule have allowed ISIS-K to spread its influence on nearly all Afghan provinces. Its flourishing networks have enabled the group to conduct attacks in Russia, Iran, Tajikistan, and Uzbekistan, raising significant concern in the Western world. ISIS-Sinai, responsible for 255 attacks in Egypt’s Sinai region, has diminished in activity over the years but remains active in the area.
Al Qaeda remains a significant threat despite global counterterrorism efforts that have weakened but not entirely eradicated its capacity. U.S. operations have targeted Al Qaeda and its global networks since the September 11 attacks, leading to the deaths of key leaders Osama Bin Laden and Ayman al-Zawahiri. Nevertheless, Al Qaeda has demonstrated remarkable resilience. For instance, its branch in Iraq, which emerged after the 2003 U.S. invasion, eventually gave rise to ISIS. Today, Al Qaeda uses a strategy of localization, merging local jihadist groups under an umbrella. One notable example is Jamaat al-Nusra wal Muslimin (JNIM), formed in the early 2010s through the merger of four jihadist groups in the Sahel region. The political instability following recent coups in Mali, Burkina Faso, and Niger has provided JNIM with opportunities to expand its operations. JNIM is known for using complex tactics to target military forces in these countries, and the GRID has recorded an increase in JNIM attacks in the Sahel and neighboring countries like Togo and Benin.
In Somalia, the Al Qaeda affiliate Al Shabaab continues to control territory and carry out attacks against military and international targets in Mogadishu. The group has recently started using vehicle-borne improvised explosive devices (VBIEDs) and suicide bombings in its operations. Al Qaeda’s affiliates in Syria, such as Hurras al-Din, Ahrar al-Sham, and Hay’at Tahrir al-Sham, remain active, though their attack numbers have decreased. In Yemen, Al Qaeda in the Arabian Peninsula (AQAP) is still operational, but its activity has also declined. Al Qaeda’s operational capabilities in Africa, including the use of mines and drones, make it a more significant threat compared to ISIS affiliates.
In Afghanistan, Al Qaeda is experiencing a resurgence under the Taliban’s rule. The Haqqani Network, an Al Qaeda affiliate, wields considerable influence, with its leader serving as the Afghan Minister of the Interior. The killing of Ayman al-Zawahiri in Kabul in 2022 highlighted the Taliban’s tolerance of Al Qaeda’s activities. This environment has also led to an increase in terrorist attacks in Pakistan, with Tehrik-i-Taliban Pakistan, another Al Qaeda affiliate, responsible for over 300 attacks in the first half of 2024.
The question of whether ISIS and Al Qaeda still pose a severe threat to the U.S. often underestimates their capabilities. Many believe these groups are confined to their regions of operation and that U.S. law enforcement’s efforts to manage these risks reduce their threat level. However, the extensive data on attacks and casualties attributed to ISIS and Al Qaeda shows that international terrorism remains a significant concern for U.S. security.
State-sponsored Terrorism
The U.S. Department of State designates Cuba, North Korea, Syria, and Iran as state sponsors of terrorism, with Iran being particularly influential. Iran has significantly expanded its political and military influence in the Middle East, especially in Yemen, Iraq, Syria, and Lebanon. The Hamas attacks on October 7 highlighted the extensive operational reach of Iranian-backed groups. These militias, including those supporting Bashar al-Assad in Syria, have become increasingly active in Iraq. According to GRID, from 2018 to 2023, 19 out of 28 recorded terrorist perpetrators in Iraq were affiliated with Iran-backed groups such as Ahel Al-Ma’rouf, Al Sabiqoon, Asa’ib Ahl al-Haqq, Ashab al-Kahf, Kata’ib Hizballah (KH), Liwa Ahrar al-Iraq, and the Operations of Martyr Ali Mansour. The State Department has designated some of these groups, including Kata’ib Hizballah and Asa’ib Ahl al-Haqq (AAH), as terrorist organizations.
Iran also supports the Houthis in Yemen, who have seized significant territory, including the capital. Houthis have targeted commercial vessels and Israeli towns in the Red Sea. In response to the October 7 attacks, Iran formed the Islamic Resilience in Iraq (IRI), which has been involved in attacks on U.S. interests. From October 7 to December 31, 2023, IRI conducted 107 attacks, including 69 in Syria, 35 in Iraq, 2 in Israel, and 1 in Jordan, mostly using missiles and drones. Many of these attacks were intercepted or failed to hit their targets. Additionally, Hezbollah has intensified its operations, conducting 238 attacks from October 7 to December 31, 2023, and over 400 attacks in the first half of 2024, primarily targeting the Israel Defense Forces (IDF) and civilians.
To conclude, there is a troubling rise in domestic, international, and state-sponsored terrorism simultaneously. The U.S. has not encountered such a convergence of threats in recent history. Far-right extremist groups, particularly anti-government militias, are becoming a significant focus for government agencies. These militias are not only active but are also increasingly adept at radicalizing individuals through social media. Meanwhile, ISIS and Al-Qaeda are expanding their reach and capabilities, posing significant risks to American interests abroad. Although their ability to strike directly within the U.S. may be limited, their affiliates present a persistent threat in their areas of operation. Most concerning is state-sponsored terrorism, especially from Iran-backed militias. Supported by Tehran, these groups have proliferated across the Middle East and are armed with advanced weaponry such as unmanned aerial vehicles (UAVs) and missiles. It is evident that terrorism, in its various forms, will remain a central issue for U.S. policymakers in the coming years.