Key Trends in Terrorism

Technology and tactics play an important role in shaping terrorist capabilities and threats. This section examines four specific areas at the intersection of technology and tactics. It finds that although there are some specific areas of concern, in the West terrorist activity continues to rely upon less sophisticated forms of attack including firearms, bladed weapons, and vehicular ramming. Explosives continue to be an issue though not all plots involving explosives are of the same sophistication. Chemical, biological, radiological, and nuclear weapons remain absent from jihadist attacks but a few plots warn against dismissing the potential for chemical and biological attacks. Drones continue to be one of the most significant areas of jihadist technological and tactical innovation and continue to spread in use.

The United States should expect unsophisticated and low-technology forms of violence (reliant on firearms, knives, and vehicular rammings) to remain the most common type of terrorist violence in the West.¹ Of the eight jihadist attacks in the West in 2019 identified by New America, only one involved explosives. In six of the eight attacks, a knife or other bladed weapon was used. In one attack, the perpetrator attempted but failed to carry out a vehicular ramming.

New America only recorded one attack involving vehicular ramming in 2019 (the Rondell Henry case in which Henry allegedly stole a U-Haul and was looking for potential targets) and the attack was foiled while still in the preparation phase. However, vehicular ramming is likely to remain a threat as illustrated by its adoption by attackers inspired by a range of ideologies, including a January 1, 2019 attack in Japan that injured nine people and which the perpetrator said was retaliation for the use of the death penalty against members of Aum Shinrikyo.²

Of the 108 jihadist attacks in the West since 2014 identified by New America, only 18 have involved explosives. Of the 14 deadly jihadist attacks in the United States since 9/11, only two involved explosives. In contrast, 10 involved firearms.

Explosives and TATP ³

The attacks involving explosives in the West since 2014 can be divided into two categories: 1) those involving TATP, triacetone triperoxide, which has long been the bomb of choice for jihadists in the West due to the ease of acquiring the components to make it, as compared to military-grade explosives; and 2) those involving improvised explosives. Seven of the eighteen attacks in the West involving explosives since 2014 involved TATP. Eleven involved other improvised explosives.

TATP can be built using the common household ingredient hydrogen peroxide, which is used to bleach hair. Though generally more accessible than military grade explosives in the West, making a TATP bomb is tricky because the ingredients are highly unstable and can explode if improperly handled. The danger of building TATP bombs without training can be seen in the case of Matthew Rugo and Curtis Jetton, 21-year-old roommates in Texas City, Texas.⁴ They didn’t have any bomb-making training and were manufacturing explosives in 2006 from concentrated bleach when their concoction blew up, killing Rugo and injuring Jetton. The pair had no political motives: They had just wanted to blow up vehicles for fun.

TATP therefore can indicate that a perpetrator received training or direction from a foreign terrorist group. Indeed, three of the seven attacks involving TATP since 2014—the 2015 Paris bombings, the 2016 bombings of the Brussels metro and airport by the same ISIS cell, and the 2017 bombing of an Ariana Grande concert in Manchester, England—were directed by ISIS. This accounts for half of the attacks known to have been directed by foreign terrorist organizations in the West since 2014 and all of the directed attacks that involved explosives.

The four other attacks since 2014 involving TATP—the September 2017 bombing at the Parsons Green tube station in London in which the bomb failed to fully explode, the August 2017 attacks in Barcelona where traces of TATP were found at a suspected bomb factory tied to the plot, a June 2017 failed bombing of the Brussels metro that killed only the perpetrator; and a May 2019 attack in which a 24-year-old Algerian man exploded a bomb that included TATP in Lyon, France injuring 14 people—had no known operational link to ISIS.⁵ These attacks account for less than 5 percent of all inspired or enabled attacks and only a third of inspired or enabled attacks involving explosives.

All of the attacks involving TATP occurred in Europe and none occurred in the United States. This may be another sign of the greater development of and diffusion of expertise and technology in jihadist networks in Europe compared to the United States.

Eight ISIS-inspired attacks and three ISIS-enabled attack in the West since 2014 used other explosives. For example, Tashfeen Malik and Syed Rizwan Farook, who killed 14 people in San Bernardino, Calif., had built pipe bombs using Christmas lights and smokeless powder.⁶ They learned the bomb recipe they used from Inspire, the English-language propaganda magazine of Al-Qaeda in the Arabian Peninsula, whose article “Make a Bomb in the Kitchen of Your Mom” was also used by the Boston Marathon bombers.⁷

Weapons of mass destruction have continued to be absent in attacks by jihadist terrorists in the West. Of 108 attacks conducted by jihadists in the West since 2014, none involved chemical, biological, radiological or nuclear (CBRN) weapons. In its 2018 report, Europol noted, “As in previous years, no terrorist attacks using chemical, biological, radiological or nuclear (CBRN) substances were recorded in the EU in 2017.”⁸ The 2019 report provides no cases of such attacks in 2018.⁹ Of the 479 people in the United States accused of jihadist terrorism-related crimes since 9/11, none acquired such weapons.

Despite the lack of CRBN attacks and greater innovation and interest on the low but deadly end of terrorist technology, jihadists have little compunction about using such weapons, as demonstrated by a series of recent plots.

For example, in 2019 Europol reported “several disrupted plots” involving attempts to produce explosives and CRBN as well as an increase in propaganda related to such weapons.¹⁰ Europol noted three plots in 2018 involving CRBN weapons.¹¹

Two of the 2018 plots mentioned by EUROPOL involved the biological toxin Ricin. In June 2018, German authorities arrested a Tunisian man who allegedly had successfully created ricin and was plotting to use it in an attack in Germany.¹² In May 2018, an Egyptian was arrested in France, who had tutorials on how to make ricin.¹³ There was also one case in the United States involving jihadists and ricin. In June 2018, the United States arrested Waheba Dais, a 45-year-old woman and legal resident who helped spread instructional material regarding ricin online.¹⁴

The threat from jihadists interested in ricin should not be exaggerated. Ricin makes a poor mass casualty weapon, as it has to be ingested to be deadly.¹⁵ Though numerous militants have expressed interest in ricin or even produced it, there have been few if any deaths as a result of ricin attacks: A 2010 Department of Homeland Security document lists only one such case—the 1978 assassination of Bulgarian dissident Georgi Markov in London.¹⁶

The third 2018 plot involving chemical or biological weapons listed by Europol revolved around a Lebanese citizen arrested in Italy who plotted to poison water supplies and was connected to another individual in Lebanon.¹⁷

Likely the most concerning recent plot involving chemical weapons is the 2017 Sydney plot in which Australian law enforcement discovered hydrogen sulfide precursors among the materials held by plotters who were in communication with a senior ISIS figure and virtual recruiter located in Syria.¹⁸

Historically, al Qaeda-linked attackers have lacked backgrounds that would aid in the development of biological weapons. An examination of the educations of the 79 terrorists responsible for some of the worst anti-Western al-Qaeda attacks¹⁹ (the World Trade Center bombing in 1993, the Africa embassy bombings in 1998, the 9/11 attacks of 2001, the Bali nightclub bombings in Indonesia in 2002, and the London bombings on July 7, 2005) found that only one had obtained a degree in biology. One of the three masterminds of the Bali bombings, Aris Sumarsono, better known as Zulkarnaen, had studied biology at an Indonesian college and is among the top leaders of the al-Qaeda affiliated group Jemaah Islamiyah.²⁰

Other evidence points to a continued lack of sophistication when it comes to CBRN weapons. In its 2018 report, Europol noted that most of the propaganda urging CBRN attacks in Europe focused on dual-use toxic chemicals rather than more sophisticated weapons.²¹

ISIS had the opportunity to acquire cobalt-60, a highly radioactive material that it could have used to build a radiological “dirty bomb” when it overran Mosul in 2014, but did not take advantage of the opportunity.²² Actual nuclear weapons remain well beyond the development capabilities of jihadist groups.

Terrorists instead continue to prefer the old standby weapons of bombs and firearms. The innovation that has occurred in weaponry and tactics used in attacks in the West has been almost entirely on the low end, through the adoption of vehicle rammings and stabbings. This is likely because such methods have proved to be just as effective at creating mayhem and murder without a need for technical know-how or training. Even so, the recent plots involving ricin and other CBRN weapons suggest that it is an important area to keep an eye on while avoiding overhyping the threat.

The United States should expect the use of armed drones by terrorist groups and other non-state actors to expand and remain a substantial aspect of the threat environment. In August 2018, Venezuelan President Nicolas Maduro was the target of a bungled assassination attempt utilizing two quadcopter drones rigged with explosives during a speech in Caracas.²³ He blamed far-right political opponents for what he called an assassination attempt.²⁴ This imaginative, yet forbidding, attack has not only raised concerns over the possibility of taking out a head of state with drones, but the possibility of attacks at public events, parades, sporting events, etc. Already, groups such as ISIS, Hezbollah, the Houthis in Yemen, and Hamas, among others, have all used drones in varying capacities, such as intelligence, surveillance, target acquisition, and reconnaissance (ISTAR) and armed attacks.²⁵

ISIS has deployed drones extensively. In January 2017, ISIS announced in its newsletter “al-Naba” the establishment of the “Unmanned Aircraft of the Mujahideen,” an operational unit organized to engineer and deploy drones in combat.²⁶ The terror network has been experimenting with drone technology since at least 2015, when Kurdish fighters in Syria shot down two small commercial drones reportedly belonging to the group—both of which were armed with explosives.²⁷

Since losing its territory in early 2019, ISIS’ threat has largely been reduced, but its full defeat should not be assumed. It is one of many groups that has masterminded ways to infiltrate trade networks to acquire commercial drones for its use. ISIS alone has been able to insert itself into a complex trade labyrinth that has given it access to drones and drone parts from at least 16 companies across seven countries.²⁸ One of the more recent accounts of these acquisitions was in September 2018 when two individuals were arrested in Denmark for attempting to ship drones to ISIS.²⁹

The Houthi rebels in Yemen have also been actively using drones. In the first half of 2019, they have attacked the Jizan and Abha airports³⁰ in southern Saudi Arabia, as well as Saudi oil pipelines.³¹ The multiple airport attacks have led to significant civilian injuries. This escalation does not show signs of stopping in the near future.

Though ISIS and the Houthis are the clearest cases of sustained armed drone campaigns by non-state actors, numerous other groups have used drones in combat or maintain the capability to do so. Non-state actor UAV use has been seen in as many as twenty countries or territories, but only a fraction are used as weapons.³² In most cases, UAV use has been for intelligence, surveillance, target acquisition, reconnaissance, or logistics, and often used for criminal activities such as trafficking or smuggling.³³ In November 2018, Nigeria’s president announced that Boko Haram had acquired and begun using drones.³⁴ In July 2018, Russia claimed that one of its military bases in Syria was again attacked by drones,³⁵ though the responsible group is unknown. The PKK used drones against Turkish soldiers in August 2017.³⁶

Hezbollah and Hamas were early adopters of drone technology and maintain an armed drone capability. In 2004, Hezbollah flew a military-grade drone, reportedly acquired from Iran, over Israeli airspace.³⁷ The Lebanese militant group also conducted strikes in Syria in 2014 with an armed drone and in 2016 with over-the-counter drones armed with small explosives.³⁸

Terrorist use of drones, whether as part of military campaigns or as one-off attacks, is likely to continue and be an important area of terrorist innovation to monitor. United Nations guidance highlights a few points that should be considered when looking to address why non-state actors use drones: attacks, disruption, surveillance, and propaganda. ³⁹ Some ways to counter drone technology include detection and tracking systems; interdiction (jamming, lasers, nets, etc.); and interference that can be performed by ground, hand-held, and other unmanned-aerial systems.