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CHICAGO, IL - JUNE 02:  A sign directs travelers to a security checkpoint staffed by Transportation Security Administration (TSA) workers at O'Hare Airport on June 2, 2015 in Chicago, Illinois. The Department of Homeland Security said that the acting head of the TSA would be replaced following a report that airport screeners failed to detect explosives and weapons in nearly all of the tests that an undercover team conducted at airports around the country.  (Photo by Scott Olson/Getty Images)
CHICAGO, IL - JUNE 02:  A sign directs travelers to a security checkpoint staffed by Transportation Security Administration (TSA) workers at O'Hare Airport on June 2, 2015 in Chicago, Illinois. The Department of Homeland Security said that the acting head of the TSA would be replaced following a report that airport screeners failed to detect explosives and weapons in nearly all of the tests that an undercover team conducted at airports around the country.  (Photo by Scott Olson/Getty Images)

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    U.S. cities boost security for busy travel week

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U.S. cities boost security for busy travel week

The State Dept. issued a worldwide travel alert with concerns over the possibility of a Paris-style attack. CNN's Rene Marsh reports.

U.S. cities boost security for busy travel week

The State Dept. issued a worldwide travel alert with concerns over the possibility of a Paris-style attack. CNN's Rene Marsh reports.