Who could be behind 'sophisticated' bombing at US embassy in Turkey? Barbara Starr & Fran Townsend weigh in

People stand outside the entrance of the U.S. Embassy in Ankara, Turkey on February 1 after a blast killed two security guards and wounded several other people.
People stand outside the entrance of the U.S. Embassy in Ankara, Turkey on February 1 after a blast killed two security guards and wounded several other people.

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    'Sophisticated' bombing at US embassy?

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'Sophisticated' bombing at US embassy? 02:35

CNN's Barbara Starr & contrib. Fran Townsend on who could be behind a suicide bombing at U.S. Embassy in Ankara, Turkey.