The E-6 TACAMO (Take Charge and Move Out) consists of the E-6A, a modified Boeing 707-320B with CFM-56 engines, and the E-6B, a modified E-6A equipped with an airborne launch control system (ALCS) capable of launching U.S. land based intercontinental ballistic missiles. TACAMO airplanes support the U.S. Navy's ballistic missile submarine force. They provide survivable, reliable, and endurable airborne command, control, and communications between the National Command Authority (NCA) and U.S. strategic and non-strategic forces.