A Pentagon spokesman on Tuesday said that the U.S. military launched a "very robust investigation" into the leak of classified Afghanistan war documents, but still do not know who is responsible for releasing them. Pentagon Spokesman Geoff Morrell said during an interview with CBS's "The Early Show" that the dissemination of over 90,000 documents detailing U.S. strategy, and information about targets and war partners, including Pakistan, poses a substantial hazard to American fighting forces in the war-torn country. Morrell said the document release "involves secrets that should not be disseminated into the public domain and could potentially endanger our operations and our forces in Afghanistan." Even the most recent of the leaked documents "is at least six months old by now," he added.