Thus, on November 7, 1983, as Soviet intelligence services were attempting to detect the early signs of a nuclear attack, NATO began to simulate one. The exercise, codenamed Able Archer, involved numerous NATO allies and simulated NATO's Command, Control, and Communications (C³) procedures during a nuclear war. Some Soviet leaders, because of the preceding world events and the exercise's particularly realistic nature, feared that the exercise was a cover for an actual attack. A KGB telegram of February 17 described one likely scenario: