A Syrian woman cries as she leaves a residential block in Aleppo, Syria, reportedly hit by an explosives-filled barrel dropped by a government forces helicopter on March 18. Khaled Khatib/AFP/Getty Images hide caption

itoggle caption Khaled Khatib/AFP/Getty Images

Norwegian marines patrol the waters around the Norwegian frigate HNOMS Helge Ingstad, which was docked in Cyprus over the weekend. The frigate, and the Danish warship HDMS Esbern Snare, will escort Danish and Norwegian cargo ships transporting Syria's most dangerous chemical weapons. Pavlos Vrionides/AP hide caption

itoggle caption Pavlos Vrionides/AP

If a plan taking shape is finalized, the MV Cape Ray, managed by the U.S. Department of Transportation, will be turned into a floating chemical weapons disposal plant. U.S. Department of Transportation Maritime Administration hide caption

itoggle caption U.S. Department of Transportation Maritime Administration

In the northern Syrian city of Aleppo last month, there was a class about how to protect against chemical weapons attacks. J.M. Lopez/AFP/Getty Images hide caption

itoggle caption J.M. Lopez/AFP/Getty Images

A photo released by the Syrian official news agency SANA Thursday shows an international expert working at a chemical weapons plant in Syria. Destroying the weapons safely may require them to be moved to another country, experts say. AP hide caption

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U.N. chemical weapons experts carry samples collected on Aug. 28 from a site of an alleged chemical weapons attack near the Syrian capital Damascus. The Organization for the Prohibition of Chemical Weapons, which is dismantling Syria's chemical weapons stockpile, was awarded the 2013 Nobel Peace Prize on Friday. Reuters /Landov hide caption

itoggle caption Reuters /Landov

A United Nations vehicle carrying inspectors from the Organization for the Prohibition of Chemical Weapons (OPCW) leaves a hotel in Damascus, on Wednesday. Some 19 OPCW arms experts are in Syria and have started to destroy weapons production facilities. Louai Behara/AFP/Getty Images hide caption

itoggle caption Louai Behara/AFP/Getty Images