December 2013: A Tunisian boy waves a flag as he runs at a rally in Tunis, marking the third anniversary of Tunisia's revolution. A prominent member of the group that's credited with averting civil war in the country says the group acted "to give hope to young people." Zoubeir Souissi /Reuters /Landov hide caption

itoggle caption Zoubeir Souissi /Reuters /Landov

Fighters from the Islamic State group parade in Raqqa, northern Syria. The U.S. is considering arming Arab and Kurdish fighters who are poised to attack the Islamic State stronghold. Uncredited/AP hide caption

itoggle caption Uncredited/AP

Tunisia's National Dialogue Quartet, represented here at a news conference in 2013, won the Nobel Peace Prize on Friday for the group's contribution to building democracy after the Jasmine Revolution in 2011. Anis Mili/Reuters /Landov hide caption

itoggle caption Anis Mili/Reuters /Landov

Undersecretary of State for Political Affairs Wendy Sherman testifies before the Senate Foreign Relations Committee in 2014. Sherman was the lead U.S. negotiator on the Iran nuclear deal. She stepped down from her post last week and is now teaching at Harvard. Charles Dharapak/AP hide caption

itoggle caption Charles Dharapak/AP