ISIS believed to have as many as 17,000 fighters

But General Dempsey and Defense Secretary Chuck Hagel, who also spoke at a Pentagon news conference, gave no indication that President Obama was about to approve airstrikes in Syria.

General Dempsey also was circumspect in describing the sort of broad effort that would be required to roll back ISIS in Syria and Iraq.

“It requires a variety of instruments, only one small part of which is airstrikes,” he said. “I’m not predicting those will occur in Syria, at least not by the United States of America. But it requires the application of all of the tools of national power — diplomatic, economic, information, military.”