Ballistic Missile Defense: Threats and Challenges

One of the most critical security challenges for humankind is the existence of nuclear weapons. Nuclear-armed intercontinental ballistic missiles (ICBMs) exacerbate this challenge by making people vulnerable to sudden nuclear attack—whether deliberate or mistaken—from across the globe. According to the Department of Defense, the explosion of even a single nuclear warhead over a major U.S. city would be an enormous disaster, potentially killing a million people and reducing 100 square miles to rubble. Multiple large nuclear explosions over cities would be a catastrophe for all humanity. A natural reaction to such a threat is to consider the possibilities for intercepting and disabling nuclear-armed ICBMs before they reach their targets. The United States has been pursuing the possibility of a defense against ballistic missiles for over 65 years. However, as we explain, no missile defense system thus far developed has been shown to be effective against realistic ICBM threats.