Cold War tensions between the increasingly hawkish United States and increasingly paranoid Soviet Union had escalated to a level not seen since the Cuban Missile Crisis because of several factors like the United States' Strategic Defence Initiative (SDI), its planned deployment of Pershing II missiles in Western Europe in the March and April of 1983, and Exercise FleetEx '83, the largest fleet exercise held to date in the North Pacific and the 1983 U.S. Intervention in Grenada. The The Korean Air Flight 007 incident in 1983 had also increased paranoia on both sides of the Iron Curtain. Of all the The Able Archer exercises, Able Archer exercises '83 would almost cause WW3. Most NATO and Eastern Bloc Nations feared for the worst.