DEFCON stands for Defense Readiness Condition. It is a five-level alert system used by the United States Armed Forces to indicate the level of threat and necessary military readiness, ranging from DEFCON 5 (normal readiness) to DEFCON 1 (maximum readiness for imminent war). The system was established during the Cold War era to standardize how the U.S. military responds to perceived threats and to coordinate readiness across services. The president, in consultation with the Secretary of Defense and the Joint Chiefs of Staff, has authority to adjust DEFCON levels as conditions change, with concrete actions tied to each level (from heightened surveillance and security measures to immediate battle readiness).