PHILADELPHIA (CBS) —  There’s a new level of security protection for Thanksgiving flyers at Philadelphia International Airport.

The Transportation Security Administration (TSA) is now using specially trained K-9 units to detect explosives or dangerous substances.

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The five Passenger Screening Canines (PSCS) will mingle among passengers in ticketing and boarding areas.

TSA officials say the dogs will be sniffing around, but they are friendly, although they should not be petted.

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Each dog is trained to signal its handler if the dog detects anything suspicious.

TSA dogs are not new to the airport but, until now, they have worked largely behind-the-scenes with baggage and containers.

The new steps come as the State Department issues a warning to U.S citizens traveling abroad of possible terror attacks.

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