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WASHINGTON, DC - APRIL 02: U.S. President Barack Obama walks from the Oval Office to the Rose Garden to deliver remarks on negotiations with Iran over their nuclear program on April 2, 2015 in Washington, DC. In exchange for Iran's agreement to curb their country's nuclear proliferation, the United States would lift some of the crippling sanctions imposed. (Photo by Win McNamee/Getty Images)

WASHINGTON, DC - APRIL 02:  U.S. President Barack Obama walks from the Oval Office to the Rose Garden to deliver remarks on negotiations with Iran over their nuclear program on April 2, 2015 in Washington, DC. In exchange for Iran's agreement to curb their country's nuclear proliferation, the United States would lift some of the crippling sanctions imposed.  (Photo by Win McNamee/Getty Images)