Forecasting Costs of U.S. Ballistic Missile Defense Against a Major Nuclear Strike

How many dollars would the United States need to spend on its ballistic missile defense (BMD) for each dollar the attacker spends to launch land-based intercontinental ballistic missiles (ICBMs) armed with nuclear warheads? A hypothetical scenario is analyzed in which the United States has a functioning BMD technology and enough interceptors to distribute them in a two-layer defense with the overall system efficiency of 90%, as targeted by U.S. war planners. It is assumed that the attacker has enough missiles to deliver a range between 500 and 6000 warheads to the continental United States. Results show that in the most optimistic case for the defender, with a very high individual interceptor kill effectiveness of 90% and with perfect decoy discrimination capability, the United States would need to spend on average 8 times more than the attacker, for a total cost between $60 billion and $500 billion. With a more realistic individual interceptor effectiveness of 50% and if the system is unable to discriminate against decoys, the United States would need to spend on average 70 times more, for a total cost between $430 billion and $5.3 trillion.