Secretary of Defense Chuck Hagel (left) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey during a Pentagon briefing on Thursday. Hagel said Islamic State militants in Iraq and Syria posed a threat "beyond anything we've seen." Yuri Gripas/Reuters/Landov hide caption

itoggle caption Yuri Gripas/Reuters/Landov

This image posted on a militant website shows ISIS fighters marching in Raqqa, Syria, where the extremist group trains recruits, including Westerners. AP hide caption

itoggle caption AP

Syrians inspect a site hit by what they said were airstrikes carried out by President Bashar Assad in the Eastern Ghouta area on Aug. 3. Assad's forces continue to besiege the area near Damascus, which is still controlled by rebels. Badra Mamet/Reuters/Landov hide caption

itoggle caption Badra Mamet/Reuters/Landov

GlobalPost co-founder and CEO Phil Balboni says what he'll remember about Foley (above) is the way he showed "such incredible courage" as his captors took his life. Steven Senne/AP hide caption

itoggle caption Steven Senne/AP