Raytheon Company awarded a sub-contract from Science Applications International Corporation (SAIC) for its latest medium frequency hull-mounted sonar system. The sub-contract is part of the Defense Advanced Research Projects Agency (DARPA) Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV) program. According to the U.S. Navy , 43 nations operate more than 600 submarines; the steady increase in undersea vessels makes tracking a challenge. Raytheon's Modular Scalable Sonar System (MS3) will integrate into SAIC's prototype trimaran vessel as the primary search and detection sonar. The systemis designed to provide search, detection, passive-threat filtering, localization and tracking capabilities without requiring human operation.