A Coast Guard Transportable Port Security Boat, crewed by members of Port Security Unit 309, on a morning patrol in the Northern Arabian Gulf in support of Operation Enduring Freedom, July 30. Coast Guard PSUs merge with the Navy's Maritime Expeditionary Squadrons to form Combined Task Group 56.5, and are charged with providing harbor defense and security to ports, seaward approaches and waterways within U.S. Central Command-s area of responsibility.