While ballistic missiles were the preferred weapons for land targets, heavy nuclear and conventional weapon tipped cruise missiles were seen by the USSR as a primary weapon to destroy United States naval carrier battle groups. Large submarines (for example, Echo and Oscar classes) were developed to carry these weapons and shadow United States battle groups at sea, and large bombers (for example, Backfire, Bear, and Blackjack models) were equipped with the weapons in their air-launched cruise missile (ALCM) configuration.