A UAV helicopter build by Northrop Gruman is on deck aboard the soon to be commissioned littoral combat ship USS Coronado during a media tour in Coronado, California April 3, 2014. REUTERS/Mike Blake/File Photo

WASHINGTON (Reuters) - Northrop Grumman Corp NOC.N has been awarded a $697 million U.S. defense contract for upgrades to the EA-18G Growler and EA-6B Prowler electronic warfare aircraft for the U.S. Navy and the government of Australia, the Pentagon said on Wednesday.