ABU DHABI — A leading Gulf firm in the United Arab Emirates whose plans to operate six U.S. ports was last year rebuffed by Congress, has been certified as a partner in a U.S. port security program. The state-owned Dubai Ports World has been certified as a partner in the Customs-Trade Partnership against Terrorism. DP World underwent a successful audit that determined the company met international ISO 28000 security standards required by C-TPAT. In 2007, DP abandoned plans to purchase a British company that operated six major ports in the United States, Middle East Newsline reported. Congress was opposed to...