Lockheed Martin and Northrop Grumman told the U.S. Justice Department Friday that the proposed merger of the defense giants is not anti-competitive and the government will benefit from savings of at least $1 billion a year.

The answer to a complaint by the Justice Department, which is seeking to block the $8.3 billion merger, was filed jointly in Washington, D.C. The companies argued that by selling certain businesses, the deal wouldn't hurt competition.The filing estimated the savings at "hundreds of millions of dollars," while the companies said in a press release that the cost savings would exceed $1 billion annually and most of that would be passed on to the U.S. government.

The filing said the merger would create a stronger competitor for Boeing, which is seven times larger than Lockheed Martin in aircraft, and twice as large in military aircraft.

Northrop Grumman would help Lockheed Martin compete.