Terrorists, Or Just Deranged?

terrorism,” he said.

The spectrum of terrorism now includes attacks loosely inspired by the Islamic State, those carried out by its affiliate groups and attacks directed by the group’s leadership. All have drawn public condemnation, but the plots executed by the Islamic State usually prompt greater concern from the authorities.

A July 16 bulletin on the Islamic State’s Amaq News Agency channel described Mr. Lahouaiej Bouhlel as a “soldier of the Islamic State” who answered a call to attack nations involved in the military campaign against the group. But the bulletin gave no specifics about the extent of his ties to the terrorist network.

On one hand, there is good reason for government officials to make immediate assumptions after some mass killings that the Islamic State has played a role, however indirect. The group’s ideology appears to have inspired a scourge of violence for more than a year, including the shooting in December in San Bernardino, California; the mass killings last month at a gay nightclub in Florida; and the deadly attack this month at a cafe in Bangladesh. These were in addition to attacks that top Islamic State operatives apparently planned directly, like the Paris assaults in November and the Brussels bombings in March.

In September 2014, the spokesman for the Islamic State called