During the postwar era, ASW continued to advance, as the arrival of nuclear submarines had rendered some traditional techniques less effective. The superpowers of the era constructed sizable submarine fleets, many of which were armed with nuclear weapons; in response to the heightened threat posed by such vessels, various nations chose to expand their ASW capabilities. Helicopters, capable of operating from almost any warship and equipped with ASW apparatus, became commonplace during the 1960s. Increasingly capable fixed-wing maritime patrol aircraft were also widely used, capable of covering vast areas of ocean. The Magnetic Anomaly Detector (MAD), diesel exhaust sniffers, sonobuoys and other electronic warfare technologies also became a staple of ASW efforts. Dedicated attack submarines, purpose-built to track down and destroy other submarines, became a key component as well. Torpedo carrying missiles, such as ASROC and Ikara, were another area of advancement.