ISIS is planning additional “significant” external operations against the West from its de-facto capital in Raqqa, Syria, the top U.S. commander in Iraq told reporters Wednesday.

“I will say that we actually aren’t sure how pressing it is, and that’s what’s worrying us,” Lt. Gen. Stephen Townsend said via teleconference from Baghdad. “We know they’re up to something. And it’s an external plot, we don’t know exactly where, we don’t know exactly when.”

Townsend said it was important to surround Raqqa quickly to cut off ISIS because of the growing terrorist threat to the West.

Townsend would not reveal any more about the threat, but said some links include plots against the United States, France and other European countries.