This handout photo provided by the Office of the Defense Secretary (OSD), taken Aug. 19, 2014, shows a Chinese fighter jet that the White House said Friday conducted a "dangerous intercept" of a U.S. Navy surveillance and reconnaissance aircraft. Uncredited/AP hide caption

itoggle caption Uncredited/AP

A photo from March 2008 provided by the Hennepin County, Minn., Sheriff's Office shows Douglas McAuthur McCain, who was killed recently fighting alongside Islamic State militants in Syria. AP hide caption

itoggle caption AP

American Eric Harroun threatened Bashar Assad on Facebook and YouTube. He spent six weeks fighting with a rebel army, a journey that did not end well for him. ABC News/YouTube hide caption

itoggle caption ABC News/YouTube

During a speech at the American Legion's National Convention on Tuesday, President Obama again called the extremist group the Islamic State a "cancer." Charles Dharapak/AP hide caption

itoggle caption Charles Dharapak/AP

Palestinian boys at a damaged building in Rafah, the Gaza Strip, on Thursday. U.S. attempts to broker a comprehensive peace deal have again been shelved as Israel and Hamas have waged their third round of heavy fighting in Gaza in the past six years. Ibrahim Khatib/Barcroft Media/Landov hide caption

itoggle caption Ibrahim Khatib/Barcroft Media/Landov

This handout photo provided by the Office of the Defense Secretary (OSD), taken Aug. 19, 2014, shows a Chinese fighter jet that the White House said Friday conducted a "dangerous intercept" of a U.S. Navy surveillance and reconnaissance aircraft. Uncredited/AP hide caption

itoggle caption Uncredited/AP

Peshmerga fighters inspect the remains of a car bearing an image of the trademark jihadist flag, after it was targeted by an American airstrike in the village of Baqouba, north of Mosul. The car reportedly belonged to Islamic State militants Ahmad Al-Rubaye /AFP/Getty Images hide caption

itoggle caption Ahmad Al-Rubaye /AFP/Getty Images