Homeland Security Director Michael Chertoff on Sunday defended the government's security review of an Arab company given permission to take over operations at six major U.S. ports. "We make sure there are assurances in place, in general, sufficient to satisfy us that the deal is appropriate from a national security standpoint," Chertoff said on ABC's "This Week." London-based Peninsular and Oriental Steam Navigation Co., was bought last week by Dubai Ports World, a state-owned business from the United Arab Emirates. Peninsular and Oriental runs major commercial operations in New York, New Jersey, Baltimore, New Orleans, Miami and Philadelphia. U.S. lawmakers...