The Navy has ordered two 155mm land attack guns from BAE Systems for the last of the three Zumwalt-class (DDG-1000) destroyers under construction.

The Navy announced the $24-million contract option on Monday that allows BAE to supply the Advanced Guns Systems (AGS) for the DDG-1002, which will be named the USS Lyndon B Johnson. BAE built the massive guns for the first two ships in the class.

The AGS is designed to fire the Long Range Land Attack Projectile (LRLAP) at a rate of 10 rounds per minute against targets on land or close to shore in support of ground forces. The fully automated weapon has a range of 83 nautical  miles, according to BAE.

Construction on the DDG-1002 began at General Dynamics’ [GD] Bath Iron Works in Maine in April and it is scheduled for delivery in 2018. The first two ships, the futures USS Zumwalt (DDG-1000) and USS Michael Monsoor (DDG-1001), are respectfully scheduled for delivery in 2014 and 2015.

Raytheon [RTN] is the systems integrator for the ships.