The strategy of the Cold War was that of containment, and it was a generation dominated by the threat of total world annihilation through the use of nuclear weapons. Deterrence was a part of containment via retributive intimidation from the risk of mutually assured destruction. As a consequence, it was also a war in which attacks were not exchanged between the two main rivals, the United States and the Soviet Union. Instead, the war was fought through proxies. Instead of mainly being confined to Europe or the Pacific, the entire world was the battlefield, with countries rather than armies acting as main players. The only constant rule was that troops of the Soviet Union and the United States could not overtly fight with each other. Military strategy involved bipolar powers with global actors who could strike an opponent with nationally debilitating destruction in a matter of minutes from land, air, and sea.