October 29, 2011: The Japanese Navy has ordered a dozen American AQS-24A mine-hunting systems. These will be carried by MCH-101 helicopters. In use, the AQS-24A, which looks like a torpedo with extra fins and attachments, is lowered into the water and dragged by the helicopter at speeds of up to 34 kilometers an hour. The AQS-24A contains a high resolution sonar that seeks out mines than lay on the sea bottom, waiting for ships to pass over. The bottom mine then detonates if a ship type it was programmed to attack is detected. The U.S. Navy has been using this mine hunting approach since the 1980s, and Japan had used an older model of the sled on a larger helicopter. Most countries still use small ships, equipped with sonar, for mine hunting. The original sled system went through several major upgrades and is considered very reliable and effective.

Meanwhile, the U.S. Navy has developed a complementary system, ALMDS (Airborne Laser Mine Detection System). Designed to operate from the MH-60S helicopter, ALMDS uses a Laser Imaging Detection and Ranging blue-green laser to detect, and identify naval mines near the surface. Unlike the AQS-24A, ALMDS operates from the low flying, and smaller, helicopters. Surface mines are either moored (via a chain to the bottom) or floating (a favorite terrorist tactic), and many float just below the surface. The laser works very quickly, and enables the ALMDS equipped helicopter to quickly check out large areas for surface mines. Terrorists have used naval mines before, of the floating variety. Navies tend to use the more sophisticated, expensive and hard-to-get bottom mines (that lie on the bottom, in shallow water).