Over the previous few weeks, he’d made a number of large withdrawals from a Russian bank account and placed repeated calls to a few people in Syria. More recently, he rented a truck, drove to Orlando, and visited Walt Disney World by himself. As numerous security videos indicate, he did not frolic at the happiest place on earth. He spent his day taking pictures of crowded plazas and gate areas.

None of Fikri’s individual actions would raise suspicions. Lots of people rent trucks or have relations in Syria, and no doubt there are harmless eccentrics out there fascinated by amusement park infrastructure. Taken together, though, they suggested that Fikri was up to something. And yet, until about four years ago, his pre-attack prep work would have gone unnoticed.