Mail Bombing: A Historical Overview of Patterns and Trends

Between November 24 and December 1, 2022, six package bombs were mailed across Spain to politicians and targets linked to the war in Ukraine. One device injured an employee at the Ukrainian embassy in Madrid, while another was discovered at the Instalaza arms company in Zaragoza, which manufactures the C90-CR (M3) anti-tank weapon being supplied to the Ukrainian military. The remaining bombs targeted the Spanish Prime Minister Pedro Sanchez, the US Embassy, the Defence Ministry, and the European Union Satellite Center near Madrid.

In January 2023, Spanish police arrested a 74-year-old suspect in Miranda de Ebro and accused him of sending the letter bombs to pressure Spain to drop its support for Ukraine. Although American and European officials initially indicated the white supremacist Russian Imperial Movement could have been involved, and directed by Russian intelligence officers, there is so far no evidence of external involvement.

Letter bombs have been used as a tactic of terror and intimidation since the early twentieth century. Their use peaked in the 1970s and 1990s before steadily declining in recent decades. Although the vast majority of letter bomb attacks are non-fatal, the Spanish mail bombing attacks are a reminder of their persistent threat. They pose major serious security concerns for government organizations, diplomatic embassies, and businesses, retaining the capacity for widespread disruption and intimidation. This article will provide an overview of mail bombings during the last two decades, identifying typical trends and patterns of letter bomb use by groups in Europe and North America.

The Use of Mail Bombs by Terrorist Organisations
Several terrorist organizations continue to use mail bombing to maintain operations or gain publicity without needing substantial resources. Letter bombs are typically crude devices that require less skill to make and offer a low-risk means of striking targets that groups may otherwise lack the ability to reach, offering an attractive option to weak or fledgling terrorist groups.

There are two main patterns that can be observed when letter bombs are deployed. Firstly, although they often target individuals within a range of institutions or organizations, including government offices, international organizations, business/industry targets, military, police, or prisons, they are hardly ever used as a method of assassination. Devices often contain low levels of explosives or can even be designed not to detonate, indicating the main intention behind letter bombs is often not to kill, but to intimidate, send a message, and gain media attention.

Secondly, groups can often send more than one letter bomb at a time as part of the same ‘volley’ against multiple targets. This increases the chances of hitting at least one target successfully and exploits the surprise factor of lowered vigilance across postal sorting offices. It also increases the messaging impact and publicity of attacks. However, mailing several devices also creates more chances for a package to be detected, which can cause increased scrutiny and further interceptions. Delivery times will also often vary, and the first blast can subsequently raise alert levels and increase screening among additional targets.

In 2003, the Italian Informal Anarchist Federation (FAI) claimed responsibility for a letter bombing campaign against European Union institutions dubbed “Operation Santa Claus”, with seven devices mailed to Italy, the Netherlands, Belgium, Germany, and the UK. The targets included Europol, Eurojust, and presidents of the European Commission and European Central Bank. All devices were sent during a window of just a few days from Bologna. Most devices were intercepted and the few which were successfully delivered only caught fire once opened, causing no injuries.

Throughout the period between 2004 to 2013, the FAI sent more devices to Italian police, prison administration, army, business, and government targets, injuring several. In these attacks, they similarly sent multiple letter bombs at a time addressed to different targets in ‘volleys’. In 2010, the group attacked international targets again, sending a cluster of letter bombs to the Greek, Chilean, and Swiss embassies in Rome, injuring two workers. Another volley in 2011 targeted Josef Ackermann, chief executive of Deutsche Bank, the Greek Embassy in Paris, and the director of the Italian state tax-collection agency Equitalia, seriously injuring him.

The Greek ‘Conspiracy of Fire Cells’ or ‘Conspiracy of Cells of Fire’ (SPF) is another insurrectionary anarchist group that uses letter bombs. Their attacks follow a similar pattern to the FAI with simultaneous volleys dispatched to many targets. In 2010, the group sent 14 parcel bombs at once to the Bulgarian, Chilean, German, Mexico, Russian, Swiss, and Dutch embassies across Athens and to several high-profile European leaders including Angela Merkel and Silvio Berlusconi. The devices contained non-lethal amounts of explosives and only slightly injured one courier, yet they caused significant disruption, sparking a massive police operation with Greek authorities temporarily halting international air mail.

The SPF launched another wave of attacks with ten mail bombs in 2017, injuring one at the Paris offices of the IMF while another device reached the German Minister of Finance before being defused. The remaining eight packages were addressed to European officials but subsequently intercepted after the Paris blast at a Hellenic Post sorting office.

Dissident republicans in Northern Ireland have also deployed letter bombs, mostly throughout the 2010s, using the same ‘volley’ method as insurrectionary anarchists. In October 2013, the New IRA sent four devices simultaneously to government and police officials in NI. All were intercepted or defused. Another wave in February 2014 targeted Army recruitment centers across the mainland UK, with seven devices sent in the space of just one week and two more sent simultaneously to prisons in NI the following month.

Their latest campaign in 2019, involved a volley of five incendiary packages sent to key transport hubs across London and the University of Glasgow, causing a major security alert. The devices were viable but only contained small amounts of explosives. While the New IRA have stronger militant capabilities than European anarchist groups, also carrying out IED and shooting attacks during the same period, mail bombing allowed them to carry out actions targeting the mainland UK, valuable operations they perhaps could not have achieved by other means.

Insurrectionary anarchists and dissident republicans appear to be the only actors to continue using mail bombs. Jihadist organizations have generally not embraced the tactic against the West during 20 years of the War on Terror, other than a high-profile plot connected to al Qaeda in the Arabian Peninsula which saw explosives hidden in printer cartridges sent from Yemen destined for targets in the United States. Although the incident attained widespread media attention and led to major security overhauls, the attack plot was an outlier. Similarly, while neo-Nazi groups orchestrated letter bomb campaigns throughout the 1990s in Europe, contemporary far-right organizations do not appear to have launched any mail bombing attacks in the last two decades.

Lone Attackers
Serial mail bombers active over extremely long periods, as Unabomber Ted Kaczynski was during a seventeen-year bombing campaign, are rare. However, lone letter bombers are more likely to attack more frequently with short pauses between individual attacks. This can be observed with serial attackers, such as the 2018 Austin serial bomber or the 2002 Midwest pipe bomber, who each operated over several weeks. Another example is Miles Cooper, who sent seven letter bombs from January 18 to February 7 2007 throughout the UK to institutions and organisations he believed were connected to monitoring and surveilling society.

However, this is not always the case, some attackers have flooded targets with a brief volley of devices. In October 2018 the ‘MAGA-bomber’, mailed sixteen crudely made pipe bombs to prominent Democratic Party politicians, critics of Trump, and donors and activists including Hilary Clinton, George Soros, and Robert De Niro. All devices were sent over just a couple of days and contained low amounts of explosives. Notably, other than a single 2004 attack committed by two neo-Nazi brothers, which injured three at a local office handling racial discrimination complaints in Scottsdale, Arizona, letter bombing cases confirmed as right-wing extremist attacks have been rare, despite the overall rise in far-right extremism.

Meanwhile, lone jihadist attackers have also refrained from letter bombing in Europe and North America. In 2010, an Islamist-inspired attacker accidentally blew himself up and was seriously injured in a Copenhagen hotel room while assembling a letter bomb he planned to send to a newspaper that published cartoons of the Prophet Muhammad. However, beyond this incident, jihadist letter bombings in Europe and North America appear almost non-existent.

Conclusion
Mail bombs are typically crude and rarely produce fatalities or significant damage but remain an enduring and attractive tactic for their low risk and high messaging power, especially for groups with limited capabilities. Groups to have used use the tactic mostly include European insurrectionary anarchists in Italy and Greece and dissident republicans in Northern Ireland. Despite the dominance of far-right and jihadist terrorism in recent decades, letter bombs have not gained traction as a common tactic among groups or individuals who adhere to either ideology.

When devices are dispatched by groups, they are often mailed alongside multiple devices addressed to several targets simultaneously over a few days to increase publicity and maximize the messaging power of the attacks. Although sometimes letter bombs are sent individually to one specific target, such as an SPF letter bomb attack that injured Former Greek PM Lucas Papademos in 2017, this is often rare, demonstrating the intention of letter bombs is typically for propaganda purposes, sending a message or serving as a reminder of groups presence and cause.