From all that can be gleaned from the record of the past fourteen plus-years, the U.S. appears to be less vulnerable to another mass-casualty attack than it was on 9/11. There have been some thwarted attempts to carry out large-scale attacks since 2001—e.g., Umar Farouk Abdulmutallab, the Nigerian “underwear bomber” tried to blow up an airplane en route to Detroit in 2009, an attack, which, if successful, would have killed 290 people. But most successful terrorist attacks on American soil have been smaller-scale events—e.g., Maj. Nidal Hasan, the Army psychiatrist who killed 13 people in a shooting spree at Fort Hood in 2009; Tamerlan and Dzhokhar Tsarnaev, the Chechen immigrants who set off bombs at the Boston Marathon in 2013, killing three and injuring 264; or Mahammod Youssuf Abdulazeez, the Kuwaiti immigrant who attacked two military installations in Chattanooga in 2015, killing five service members.
Many of these attacks were inspired by Al-Qaeda in the Arabian Peninsula and in particular by Anwar al-Awlaki, the charismatic American-born jihadi who was killed by a Predator strike in 2011.
What of ISIS? The Islamic State has made a big splash since its formation in 2013. It has managed to acquire territory the size of Belgium sprawling across eastern Syria and western Iraq. But understandably most of its focus has been on internal expansion. Only now, with its black-clad fanatics consolidating control of their “caliphate,” is it starting to look abroad in a serious and disturbing way. ISIS is spawning provinces as far away as Algeria, Libya, Yemen, Nigeria, and Afghanistan. And it is inspiring attacks on far-flung targets. On September 26, 2015, for example, Islamic State’s Yemen affiliate claimed responsibility for a suicide bombing that killed 26 people at a Shiite mosque in Sanaa.
A look at a helpful map compiled by the New York Times shows that ISIS has been linked to numerous other attacks around the world in North America, the Middle East, and Europe. In North America, ISIS has been linked to only three actual attacks. On October 23, 2014, a hatchet-wielding man charged four police officers in Queens, wounding two of them before being killed. A day earlier, on October 22, an Islamic convert attacked a war memorial and the parliament building in Ottawa, killing one soldier before being gunned down. And on October 20, another Islamist radical ran over two Canadian soldiers in Montreal, killing one. Many more ISIS followers have been arrested in the U.S. and charged with plotting to carry out terrorist attacks before they could strike. Moreover, at least 250 Americans are believed to be fighting with ISIS in Iraq and Syria. Should any of them return home, these battle-hardened jihadists would represent a considerable danger.
Despite our relative success in stopping mass attacks since 9/11, we should be very worried about what these jihadists radicalized by ISIS can do. Even a series of “lone wolf” attacks could be decidedly dangerous and demoralizing; just remember how the manhunt for the Boston Marathon bombers temporarily paralyzed the Boston area.
But the danger of mass-casualty attacks has by no means disappeared. Just because one such attack hasn’t occurred in the past 14 years doesn’t mean we will remain safe indefinitely. The very nature of terrorist attacks is that they come as a surprise. Remember how shocked the nation was by 9/11 itself. It would be the height of hubris to imagine we will never be so surprised again.
That is one reason—one among many—to worry about the emergence of ISIS, which has become the hottest “brand” in terrorism, surpassing even al-Qaeda. Evil as ISIS has been in the Middle East, where it has killed American hostages along with many other innocents, it is also a growing danger to the outside world—principally the Middle East and Europe but also to the United States which is roundly (and rightly) reviled by all Islamist radicals as one of the chief obstacles to their nefarious designs.