Five ambulances, donated by the U.S. to help combat Ebola, are lined up after a ceremony attended by Sierra Leone's president, Ernest Bai Koroma, in Freetown on Sept. 10. Michael Duff/AP hide caption

itoggle caption Michael Duff/AP

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

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The chamber of the House of Representatives empties following a joint meeting of Congress with visiting Ukrainian President Petro Poroshenko on Sept. 18. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

President Obama speaks at the U.N. Climate Summit on Tuesday. Discussing America's past, Obama told the group, "We recognize our role in creating this problem." Andrew Burton/Getty Images hide caption

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President Obama and Vice President Biden on Friday debuted the "It's On Us" campaign to help colleges and universities prevent and respond to sexual assault on campus. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Ukrainian President Petro Poroshenko, joined by Speaker of the House John Boehner and Vice President Joe Biden, acknowledges lawmakers' applause after addressing a joint meeting of Congress. J. Scott Applewhite/AP hide caption

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Iranian Foreign Minister Mohammad Javad Zarif speaks during a recent news conference in Rome. Zarif told NPR that the U.S. has been hesitant and contradictory in its approach to dealing with the self-declared Islamic State. Fabio Campana/EPA/Landov hide caption

itoggle caption Fabio Campana/EPA/Landov

House Speaker John Boehner has expressed cautious support for the White House plan. He and other House GOP leaders are backing a measure to authorize the arming and training of moderate Syrian rebels. J. Scott Applewhite/AP hide caption

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Workers unload medical supplies to fight the Ebola epidemic from a USAID cargo flight in Harbel, Liberia, in August. John Moore/Getty Images hide caption

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Yemeni soldiers hold up their weapons at an area seized from al-Qaida in the southeastern province of Shabwa, Yemen, on May 8. President Obama said Wednesday that U.S. strategy against the so-called Islamic State would be similar to how it targeted militants in Yemen and Somalia. Yemen's Defense Ministry/AP hide caption

itoggle caption Yemen's Defense Ministry/AP