FILE - In this April 9, 2009 file photo, a sign outside the Lockheed Martin plant in Marietta, Ga. is shown. Lockheed Martin on Saturday, May 28, 2011 admitted it was the recent target of a "significant and tenacious" cyber attack, although the defense contractor and the Department of Homeland Security insist the hack was thwarted before any critical data was stolen. (AP Photo/John Amis, File)

Lockheed Martin has won a $391 million contract to build a radar system the U.S. Army uses to track incoming enemy fire.

The work on 33 Q-53 units to be delivered by the end of 2014 will be done in Syracuse, N.Y., Moorestown, N.J., Akron, Ohio, and Clearwater, Fla.

Bethesda, Md.-based Lockheed Martin says Monday the Army also has an option to buy 38 more units.

The Q-53 is a truck-mounted system that's been used in Iraq and Afghanistan to determine where rocket, mortar and artillery fire is coming from.