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Vienna, Austria - July 14: Signed Contract (Comprehensive Plan Of Action) of E 3+3 negotiations with signatures of Foreign Minister of China, Wang Yi, French Foreign Minister Laurent Fabius, German Foreign Minister Frank-Walter Steinmeier, EU High Representative for Foreign Affairs and Security Policy Federica Mogherini, Foreign Minister of Iran, Mohammad Javad Zarif, Russian Foreign Minister Sergei Wiktorowitsch Lawrow, British Foreign Secretary of State for Foreign and Commonwealth Affairs, Philip Hammond and US Secretary of State John Kerry on July 14, 2015 in Vienna, Austria. (Photo by Thomas Imo/Photothek via Getty Images)

Vienna, Austria - July 14: Signed Contract (Comprehensive Plan Of Action) of E 3+3 negotiations with signatures of Foreign Minister of China, Wang Yi, French Foreign Minister Laurent Fabius, German Foreign Minister Frank-Walter Steinmeier, EU High Representative for Foreign Affairs and Security Policy Federica Mogherini, Foreign Minister of Iran, Mohammad Javad Zarif, Russian Foreign Minister Sergei Wiktorowitsch Lawrow, British Foreign Secretary of State for Foreign and Commonwealth Affairs, Philip Hammond and US Secretary of State John Kerry on July 14, 2015 in Vienna, Austria. (Photo by Thomas Imo/Photothek via Getty Images)