The United States' monopoly on nuclear weapons was broken by the Soviet Union in 1949 when it tested its first nuclear explosive (Joe-1), and with this many in the US government and public perceived that the nation was more vulnerable than it had ever been before. Duck-and-cover exercises quickly became a part of Civil Defense drills that every American citizen, from children to the elderly, practiced to be ready in the event of nuclear war. In 1950, during the first big Civil Defense push of the Cold War and coinciding with the "Alert America!" initiative to educate Americans on nuclear preparedness; The adult-orientated Survival Under Atomic Attack was published and contains "duck and Cover" or more accurately, cover-and-then-duck advice without using those specific terms in its "Six Survival Secrets For Atomic Attacks" section. Try To Get Shielded 2.Drop Flat On Ground Or Floor 3. Bury Your Face In Your Arms("crook of your elbow")". The child-orientated "Duck and Cover (film)" was produced a year later by the Federal Civil Defense Administration in 1951. Education efforts on the effects of nuclear weapons proceeded with stops-and-starts in the US due to competing alternatives. In a once classified, 1950s era, US war game that looked at varying levels of war escalation, warning and pre-emptive attacks in the late 1950s early 1960s, it was estimated that approximately 27 million US citizens would have been saved with civil defense education. At the time however the cost of a full-scale civil defense program was regarded as lesser in effectiveness, in cost-benefit analysis than a ballistic missile defense (Nike Zeus) system, and as the Soviet adversary was believed to be rapidly increasing their nuclear stockpile, the efficacy of both would begin to enter a diminishing returns trend. When more became known about the cost and limitations of the Nike Zeus system, in the early 1960s the head of the department of defense determined once again that fallout shelters would save more Americans for far less money. The production of the Duck and Cover film in 1951 by the Federal Civil Defense Administration occurred during the height of the Korean War (1950-1953), and coincided with the first Desert Rock exercises in the Nevada desert which were designed to familiarize the US military with fighting alongside battlefield nuclear weapons, as it was feared that a resolution to the Korean War might need the theatre of operations to first expand across the border into the People's Republic of China and require nuclear weapons to end it.