Dura Europos, a Roman walled city in eastern Syria, dates back to 330 B.C. The main gate is shown here in a photo from 2010. It's one of the many important archaeological sites militants of the self-styled Islamic State have ransacked and damaged. EPA /Deir Ezz-Zour Antiquities Department/Landov hide caption

itoggle caption EPA /Deir Ezz-Zour Antiquities Department/Landov

These pop-up targets are part of an advanced drill, named "friend or foe," that tests shooter reaction times. Some targets have a camera, and others, like these pictured, have a gun. The shooter must decide within seconds whether to shoot. Deborah Amos/NPR hide caption

itoggle caption Deborah Amos/NPR

The most recent propaganda videos from Boko Haram have higher production values than in the past and other similarities to ISIS-produced videos. Boko Haram/Sendvid hide caption

itoggle caption Boko Haram/Sendvid

A woman kneels near a makeshift memorial for Kayla Mueller in Prescott, Ariz. Brian Skoloff/AP hide caption

itoggle caption Brian Skoloff/AP

Members of the family of Kayla Mueller, 26, have confirmed that their daughter has died. She had been held captive since being taken prisoner in 2013 while doing humanitarian work in Syria. The Mueller Family hide caption

itoggle caption The Mueller Family

Supporters of Jordanian pilot Lt. Muath al-Kaseasbeh hold posters of him that read, "We are all Muath," during a protest in Amman, Jordan, on Tuesday. Raad Adayleh/AP hide caption

itoggle caption Raad Adayleh/AP

Japan's Chief Cabinet Secretary Yoshihide Suga says the government is working to secure the release of Haruna Yukawa and Kenji Goto. A deadline imposed by the so-called Islamic State for the men's release has lapsed. Koji Sasahara/AP hide caption

itoggle caption Koji Sasahara/AP

A photo from a video clip posted on YouTube shows a man with a knife threatening two captives identified as Haruna Yukawa (right) and Kenji Goto Jogo. The Islamic State says it wants $200 million for their release. Kyodo /Landov hide caption

itoggle caption Kyodo /Landov

French Prime Minister Manuel Valls delivers his speech during an homage to the 17 victims of last week terrorist attacks, at the French national Assembly in Paris on Tuesday. Remy de la Mauviniere/AP hide caption

itoggle caption Remy de la Mauviniere/AP

Iraqi crowds cheer as the countdown and fireworks begin during a New Year's Day celebration at Firdos Square in Baghdad on Wednesday. Hadi Mizban/AP hide caption

itoggle caption Hadi Mizban/AP

Dr. Mohammed Arif helps treat a wounded patient at a field hospital in Kobani, Syria. Most of the clinics in this besieged Syrian border town are now in ruins. Only one still stands, its location kept secret lest it be targeted. Jake Simkin/AP hide caption

itoggle caption Jake Simkin/AP

A member of the Saudi border guards mans a machine gun at the border with Iraq in July. Since the so-called Islamic State launched its offensive this summer in Iraq, Saudi Arabia has sent thousands of troops to the region. Faisal Nasser/Reuters/Landov hide caption

itoggle caption Faisal Nasser/Reuters/Landov

Peter Kassig, who changed his first name to Abdul-Rahman when he converted to Islam, is shown with a truck filled with aid supplies for Syrian refugees. Courtesy of Kassig family hide caption

itoggle caption Courtesy of Kassig family

Displaced demonstrators from the minority Yazidi sect demonstrate outside the United Nations offices in Irbil, Iraq, on Aug. 4 in support of those held captive by the self-proclaimed Islamic State. Azad Lashkari/Reuters/Landov hide caption

itoggle caption Azad Lashkari/Reuters/Landov

Fighters from the Islamic State group parade down a main road in the northern city of Mosul, Iraq. A Yazidi woman nicknamed Dudu tells the story of how she was kidnapped by ISIS along with her sisters and other women, to be sold and married off. AP Photo hide caption

itoggle caption AP Photo