By MIKE MCCONNELL, MICHAEL CHERTOFF AND WILLIAM LYNNOnly three months ago, we would have violated U.S. secrecy laws by sharing what we write here—even though, as a former director of national intelligence, secretary of homeland security, and deputy secretary of defense, we have long known it to be true. The Chinese government has a national policy of economic espionage in cyberspace. In fact, the Chinese are the worlds most active and persistent practitioners of cyber espionage today.Evidence of Chinas economically devastating theft of proprietary technologies and other intellectual property from U.S. companies is growing. Only in October 2011 were details declassified in a report to Congress by the Office of the National Counterintelligence Executive. Each of us has been speaking publicly for years about the ability of cyber terrorists to cripple our critical infrastructure, including financial networks and the power grid. Now this report finally reveals what we couldnt say before: The threat of economic cyber espionage looms even more ominously.