Terrorist organizations like ISIS and al-Qaida have lost physical territory in a number of areas in the Middle East, as U.S. and allied forces fight to push them out.

Some have speculated that those battlefield losses are going to lead to more smaller-scale attacks in Europe and, potentially, the U.S.

Was that the cause of the recent bombing of the Ariana Grande concert in Manchester, England?

Katherine Zimmerman is a research fellow at the American Enterprise Institute who specializes in al-Qaida’s terrorist network, and she’s with me.