(CNN) The Pentagon’s claims in a new report that China is trying to extract sensitive information from U.S. government computers has put cyber security issues back in the media spotlight. But how serious is the threat to U.S. interests? How can America respond? And what other issues should be attracting policymakers’ attention? Cyber security expert Eugene Spafford, a professor of computer sciences at Purdue University and former member of the President’s Information Technology Advisory Committee, will be taking questions from GPS readers.