 The exercise simulated a Soviet conventional attack on European NATO forces 3 days before the start of the exercise (D-3), transitioning to a large scale chemical war (D-1) and on day 1 (D+1) of the exercise, NATO forces sought political guidance on the use of nuclear weapons to stem the Soviet advance which was approved by political leaders.NATO then began simulating preparations for a transition to nuclear war.These simulations included 170 radio-silent flights to air lift 19,000 US troops to Europe, regularly shifting military commands to avoid nuclear attack, the use of new nuclear weapon release procedures, the use of nuclear Command, Control, and Communications (C3) networks for passing nuclear orders, the moving of NATO forces in Europe through each of the alert phases from DEFCON 5 to DEFCON 1, and the participation of political leaders like Margaret Thatcher, Helmut Kohl and Ronald Reagan.