By Joseph Menn SAN FRANCISCO (Reuters) – Microsoft Corp pledged late Wednesday to fight in court against any attempt by U.S. intelligence agencies to seize its foreign customers data under American surveillance laws, one of a series of steps aimed at reassuring nervous users abroad. The maker of the worlds most popular computer operating system said it had never turned over any such data under the Foreign Intelligence Surveillance Act and did not believe that authorities are entitled to the information if it is stored abroad. We are committing contractually to not turning it over without litigating that issue, Microsoft General Counsel Brad Smith said in an interview with Reuters. Smith also said that Microsoft would dramatically increase the amount of encryption it uses for internal traffic, following similar moves by Google Inc and Yahoo Inc in the wake of reports that the National Security Agency had tapped into their facilities overseas without oversight by the Foreign Intelligence Surveillance Court.