Friday’s suicide attack outside the American embassy in Tunis is the latest in the series of relatively limited terror attacks that have dogged Tunisia since the mass shootings at the capital’s Bardo museum and the resort town of Sousse in 2015. These were followed the next year by the attempted invasion of the border town of Ben Guerdane by ISIS. Investigations revealed extensive planning and significant numbers involved in the larger attacks. The more recent attacks have been smaller in scale and more difficult to prevent for that reason, according to experts, and they represent a continued threat to Tunisia’s transition from autocracy to functioning democracy. At around 11am on Friday two men, named by radio station Mosaique FM as Zenidi Mohamed Selim and Khoubaib Laaga, approached a police patrol outside the US embassy where they detonated their payload. The explosion caused windows in office blocks 300 metres away to shake. Tunisian officials later confirmed the explosives had been rigged to the attackers' bodies and the motorcycle they were riding. Both men were killed immediately, while five members of the security services and a member of the public were injured. One officer, named as Lt Taoufik Missaoui, later succumbed to his injuries. Interior Minister Hichem Mechichi told a press conference later on Friday that the US Embassy had not been the intended target of the attack. While no group immediately claimed responsibility for the bombing, at least one of the alleged attackers is known to have been recently released from prison where he was being held on terrorism charges. Both men were born in the relatively affluent coastal suburb of La Marsa to the north of Tunis, Selim in 1991 and Laaga two years later. Selim later moved a few miles south to the suburb of Kram, while Laaga went to live in the fishing village of Sidi Daoued on the opposite side of the Gulf of Tunis. Suggestions of their links to a terror group were strengthened on Friday evening with the admission by Seifeddine Makhlouf, a member of the parliament and leader of the hardline political Islamist group, Al Karama, that his legal firm had defended Laaga after he was found to have made a Facebook post that contravened Tunisia's strict anti-terrorism laws. "The attack underscores the difficulty Tunisia faces in addressing its terrorism problem," Matt Herbert, a senior analyst at the Global Initiative Against Transnational Organised Crime, told <em>The National</em>. "Incarceration does not equate with deradicalisation. There a risk of incarceration simply further fuelling radicalism and grievance of convicted terrorists, making attacks once released more likely." Tunis has witnessed two similar bombings in the past two years. Last June, two suicide bombers targeted security services in central Tunis and at the El Gorjani barracks a few kilometres east, killing a policeman and a civilian and wounding several bystanders. In 2018, an unemployed female graduate detonated a suicide vest in central Tunis, killing herself and injuring several people nearby. “Since 2015, in Tunis, other coastal urban centres and tourist areas, the Tunisian security forces have significantly improved their ability to proactively uncover and arrest groups planning large-scale incidents," Mr Herbert said. However, while the activities of major terror cells may have been interrupted, smaller, lone wolf attacks have continued. “Today's IED seems to have been more powerful than the attacks over the last few years on Avenue Bourguiba and in front of the Gorjani barracks, but it resulted in fewer casualties than other recent incidents, underscoring the amateurish nature of the attack," Mr Herbert said. “These lone wolf attacks are extremely difficult for police to uncover and head off precisely because the number of conspirators is small, their logistical needs fairly light, and their communications limited.” Asked if Tunisia was experiencing a significant change in the nature of the threat facing it, Dr Aaron Zelin, who recently completed a book on the origins of Tunisian radicalism, told <em>The National</em>, "I don't know if it's a shift, it's more what's possible. If they had the capabilities to do more sophisticated attacks they would."