The FBI reported that the two deceased suspects traveled to Garland from Phoenix and that the agency had previously investigated one of them, a Muslim convert named Elton Simpson, for attempting to travel to Africa to fight with al Shabaab. Simpson was found guilty in March 2011 of a single count of making false statements to FBI agents. He also reportedly posted a message on Twitter before the attack pledging allegiance to the Islamic State. The second gunman has not been identified.
That there was an attack at an event involving Prophet Mohammed cartoons is unsurprising — this was merely the latest of many similar attacks that have occurred since 2006. The trend began when a group of Muslim clerics traveling through the Middle East condemned cartoons of the Prophet Mohammed that had appeared in the Jyllands-Posten in September 2005. Their statements fomented a violent, if somewhat belated, reaction. In early February 2006, Islamist rioters attacked Danish and Norwegian embassies and consulates in Syria, Lebanon, Afghanistan, Iran, Pakistan, Nigeria and Indonesia. In Damascus, rioters set fire to the Danish and Norwegian missions, and in Beirut, protesters burned the Danish Embassy. Soon after, at least nine people died when rioters tried to storm an Italian Consulate in Libya.
Al Qaeda in the Arabian Peninsula has repeatedly denounced Prophet Mohammed cartoons in its Inspire magazine, and the first edition of Inspire contained a hit list of those who had insulted Islam by depicting the prophet. In September 2007, Abu Omar al-Baghdadi, then the leader of the Islamic State in Iraq, offered a $100,000 reward for killing Lars Vilks, a Swedish artist who had recently portrayed the Prophet Mohammed as a dog in one of his cartoons. Geert Wilders, a Dutch politician set to speak at the Garland event, was also included on the list.
Since the publication of the Inspire hit list, grassroots jihadists have attacked various targets accused of defaming the Prophet Mohammed, including most prominently the Charlie Hebdo magazine. Another less publicized attack followed on Feb. 15, when a gunman targeted a free speech event in Copenhagen that featured Vilks. One attendee was killed and three police officers were wounded in that attack. The Copenhagen event, titled "Art, Blasphemy and Freedom of Expression," was similar to the event in Garland.
As with the Copenhagen event, the manner in which the Garland shooters conducted their attack indicates that they were not well trained. They appear to be the type of grassroots jihadists who are most likely to attack the United States and the West in general. Initial reports indicate that the suspects were armed with semi-automatic AK-style rifles, weapons that could be legally obtained rather than illegal weapons that would be riskier to obtain, such as automatic weapons and hand grenades. In essence, they are the kind of operatives who are hard to apprehend until they plan an attack but who, because of a lack of tradecraft, are easily stopped if proper precautions are taken.
In the case that led to Simpson's arrest, he was caught up in an FBI sting operation in which a Muslim informant from Kenya recorded conversations between them. According to a court order, Simpson told the informant he planned to travel to South Africa under the auspices of attending an Islamic seminary. Once in South Africa, Simpson would make his way to Somalia to fight with al Shabaab. Because Simpson had been caught in an FBI sting before, he was presumably more careful in planning the Garland attack.
Moreover, if it is true that Simpson was stopped from traveling to Africa to fight with al Shabaab, it would be similar to the Sept. 23 attack in Ottawa, Canada, in which Michael Zehaf-Bibeau killed a soldier at the Canadian War Memorial and stormed the Canadian Parliament building after being denied a passport to travel to Syria to fight with the Islamic State. In other words, potential jihadists may be turning to domestic targets after failing to join foreign militant groups.
Grassroots attacks like that in Garland pose the biggest jihadist threat to the United States, but they are also preventable. There are a large number of potential grassroots attackers and many possible targets. In this case, event organizers were able to stop an attack by poorly trained jihadists by providing heavy security. That foresight and planning prevented a Charlie Hebdo-type massacre.
Editor's note: An earlier version of this analysis misstated the profession of Geert Wilders.