The 1983 exercise introduced several new elements not seen in previous years, including a new, unique format of coded communication, radio silences, and the participation of heads of government. This increase in realism, combined with deteriorating relations between the United States and the Soviet Union and the anticipated arrival of Pershing II nuclear missiles in Europe, led some members of the Soviet Politburo and military to believe that Able Archer 83 was a ruse of war, obscuring preparations for a genuine nuclear first strike. In response, the Soviet Union readied their nuclear forces and placed air units in East Germany and Poland on alert. The Soviet 4th Air Army began loading nuclear warheads onto combat planes in preparation for war. The apparent threat of nuclear war ended when Lieutenant General Leonard H. Perroots advised against responding to the Warsaw Pact military activity, which ended with the conclusion of the exercise on November 11.