A depth charge is an anti-submarine warfare (ASW) weapon intended to destroy or cripple a target submarine by being dropped into the water close to its target and detonating, subjecting the target to a powerful and destructive hydraulic shock. Most depth charges use high explosive charges and a fuze set to detonate the charge typically at a preselected depth. Depth charges can be dropped by ships, patrol aircraft, and helicopters. Depth charges have now largely been replaced by anti-submarine homing torpedoes.