FILE - In this July 7, 2005 file photo file photo the wreckage of a double-decker bus with its top blown off by a bomb and damaged cars scattered on the road at Tavistock Square in central London. In the 20 years since the Sept. 11, 2001 terrorist attacks in the United States, a mixture of homegrown extremists, geography and weaknesses in counterterrorism strategies have combined to turn Europe into a prime target for jihadists bent on hurting the West. (AP Photo/Sang Tan, File)
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