The Department of Defense is preparing to implement the most sweeping restrictions yet on foreign information technology (IT) workers. This planned policy—which will cover one-third of civilian federal employees—will ban non-U.S. citizens from a wide range of computer projects. The Departments of Justice and Treasury have instituted similar restrictions on non-citizens working in certain areas. Those steps were taken prior to last September’s attacks. The DOD policy—slated for adoption within 60 to 90 days—extends restrictions on foreign nationals handling secret information to “sensitive but unclassified positions,” which include the growing number of contract workers who process paychecks, write software,...