French criminologist Alain Bauer, an advisor to several French government officials as well as to police forces in the United States, borrows an old Marxist term to describe this soft-target trend: “It’s lumpen terror, the lowest level of terror,” Bauer told The Daily Beast. “But thanks to the media even if it fails, it works. Terror is about violence and communication, and this is effective.

Why did it take so long for al Qaeda or ISIS to start random soft-target attacks in the United States?

“Because it was not good enough,” said Bauer. “It was not rewarding enough for them. You did the World Trade Center, or you attacked police or soldiers, targets you could ‘proud’ of.”

But ISIS has “changed their marketing strategy,” said Bauer. This low level terror is like “the worm that attacks the lion,” he said in a colorful metaphor. “The worm will not kill the lion, but it will make it crazy with little bites here and there.”