Pentagon officials downplayed the chances of last night's airstrikes against Raqqa, the ISIS capital if Syria, having a serious impact on the group's day-to-day operations, with Lt. Gen. William Mayville Jr. saying ISIS will quickly adapt to the air war and rebound from any losses suffered overnight.

"We have seen evidence that they have already done that," Mayville confirmed. The strikes were the first on ISIS in Syria, after six weeks of airstrikes against the group in Iraq which have, similarly, yielded very little.

Reports on the strikes in Raqqa suggest a handful of buildings were hit, and around 70 ISIS fighters were among the slain. Civilian casualties are unclear.