The Pentagon made the announcement following a closed-door hearing Thursday in which top military officers, including Panetta, testified before the powerful House Armed Services Committee.

Officials say the Pentagon has put into place a series of steps designed to limit leaks. The steps include better training on handling classified information, instructions on what constitutes a leak and what to do if one may have taken place. They are designed to complement the department's existing policies, which require Pentagon employees to report potential classified disclosures up the chain of command

In a news conference following Thursday's hearing, Armed Services Committee Chairman Buck McKeon told reporters that he did not believe the Pentagon was responsible for recent national security leaks. Those leaks include U.S. President Barack Obama's alleged push for cyber attacks on computer systems that run Iran's nuclear facilities, and procedures for targeting and killing militants overseas.

Some Republican members of Congress have suggested the leaks were made by the Obama administration to improve Obama's prospects of reelection by portraying him as tough on terrorism.

McKeon, a Republican, did not address those allegations directly. He said more than four million people have classified security clearance, and added that keeping sensitive data secret is nearly impossible in the digital age.