The U.S. Defense Department awarded Northrop Grumman Corp. a $697 million contract to upgrade two types of military aircraft.

Northrop Grumman will carry out system upgrades on the EA-18G Growler and final upgrades on the EA-6B Prowler for the U.S. Navy and the Australian government. Both planes are used for electronic warfare, such as radar jamming.

The EA-18G Growler is the successor to the EA-6B Prowler, which was retired from Navy service in 2015 but is slated to remain in Marine Corps operation through 2019.