Fleet Air Reconnaissance Squadron 4 (VQ-4), nicknamed the Shadows, is a naval aviation squadron of the United States Navy based at Tinker Air Force Base, Oklahoma. The squadron flies the Boeing E-6B Mercury airborne command post and communications relay aircraft. It is part of the U.S. Navy's TACAMO community, whose mission is to enable the President of the United States and the Secretary of Defense to directly communicate with U.S. submarines, bombers, and missile silos during a nuclear war.