SYRACUSE, N.Y. (AP) -- 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.