Pentagon ordered to preserve materials related to leak investigation June 25, 2012 -- Updated 1818 GMT (0218 HKT) "We are complying with the preservation order," a senior Pentagon official says The order potentially could cover thousands of civilian and military personnel The officials says the next step could be for personnel to be interviewed Washington (CNN) -- Defense Department officials are under a Justice Department order to preserve all e-mails and documents that may be related to the ongoing investigation into leaks to the news media of national security information, a senior Pentagon official confirmed Monday. "We are complying with the preservation order," the official told CNN. Defense Department officials may not delete or destroy any e-mails or documents that might be related to the leak investigation, said the official, who spoke on the condition of not being named. "You can't start shredding," he observed. The order potentially could cover thousands of civilian and military personnel who work on military intelligence and surveillance programs. It also could include members of the Defense Intelligence Agency and other organizations, such as the National Security Agency, which focus to a large extent on eavesdropping overseas. However, the official said the Justice Department is clear it's only interested in information related to the current leak investigation. The official said the next step could be for personnel to be interviewed. "We would certainly expect DoD officials to be interviewed" if they are likely to have information on the leaks, he said. The investigation was sparked by recent leaks of classified information, including the revelation in May that a mole had been working to help thwart a Yemen bomb plot targeting the United States, and the disclosure of the classified drone program in Afghanistan and Pakistan.