Self Defense Test Ship

The Self Defense Test Ship (SDTS) is one of the assets of the US Navy. It is a refurbished ship that is in some cases operated by remote control; that capability is designed to support self-defense engineering, testing, and evaluation.

Being unmanned, it avoids the safety constraints and other problems associated with manned ships. During typical operations, launched threats attack the ship and the combat or weapon system being tested responds to these threats, defending the ship. The prearranged attack is in practice aimed at a decoy barge pulled 150 feet behind the SDTS in case of damage. Some systems installed on the SDTS include MK 57 NATO Sea Sparrow, MK 23 Target Acquisition system, Rolling Airframe Missile, AN/SLQ-32(V) 3 ESM, and Phalanx Close in Weapon System.

The current SDTS is the former USS Paul F. Foster (DD-964), now known as Ex-Paul F. Foster, and is not a remote-controlled ship, but a test-bed for multiple initiatives, ranging from bio-fuels to lasers. She replaced the former USS Decatur (DDG-31) in 2005.

...
Wikipedia