Afghan National Security Adviser Mohammad Hanif Atmar (right) and U.S. Ambassador to Afghanistan James Cunningham exchange documents after signing the Bilateral Security Agreement, with Afghan President Ashraf Ghani (rear, left) and Chief Executive Abdullah Abdullah in the background. Jawad Jalali/EPA/Landov hide caption

itoggle caption Jawad Jalali/EPA/Landov

Ashraf Ghani (second from left) stands next to Afghanistan's Chief Executive Abdullah Abdullah (left) and two deputy officials as he takes the oath during the inauguration ceremony at the presidential palace in Kabul on Monday. Ahmad Massoud/Xinhua/Landov hide caption

itoggle caption Ahmad Massoud/Xinhua/Landov

Travelers lined up Friday to reschedule flights at Chicago's O'Hare International Airport after the region's air traffic control was sabotaged. More flights are resuming Saturday, but hundreds were also canceled. Scott Olson/Getty Images hide caption

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An A-18C Hornet attached to Strike Fighter Squadron (VFA) 87, prepares to launch from the flight deck of the aircraft carrier USS George H.W. Bush (CVN 77) to conduct strike missions against Islamic State group targets. Robert Burck/AP hide caption

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Sheik Abdullah bin Bayyah is interviewed about his fatwa explaining why ISIS is wrong to claim that Islam supports violence and the establishment of a caliphate by force. Dina Temple-Raston/NPR hide caption

itoggle caption Dina Temple-Raston/NPR

The U.N. Security Council on Wednesday unanimously approved a historic resolution aimed at ending the flow of foreign extremists to the world's conflicts. President Obama thanked the council but warned that "a resolution alone will not be enough." Julie Jacobson/AP hide caption

itoggle caption Julie Jacobson/AP