The modification exercises the option on a previously awarded contract for production, system upgrade, maintenance, management and logistical work in support of the JASSM program, the Defense Department said Friday.
Lockheed Martin will perform work in Troy, Alabama, through June 29, 2019.
The company was awarded the contract to build additional air-to-surface missiles for the Air Force in October 2015.
It also received a contract modification in December to provide JASSM support to Poland and Finland.