Forbes

Of all the missions assigned to America’s military, none has a more tortured history than missile defense of the homeland. In the 60+ years since Russia first proved it could launch intercontinental ballistic missiles—ICBMs—many, many ideas have been funded for defending the nation against them.

Most of the ideas did not work out. Politics played a part, but the biggest issue was doubt about whether missile defenses could function effectively in the midst of a nuclear war. That doubt focused mainly on the performance of interceptor missiles developed to engage and destroy incoming nuclear warheads.

Ballistic warheads hurled over intercontinental distances are tough targets to intercept. They are difficult to track and hardened against shock, traveling at hypersonic speeds of up to seven miles per second. If the attacker is reasonably sophisticated, the warheads may be accompanied by “penetration aids” like decoys designed to confuse defenders.

The challenge of destroying hundreds of such warheads in a few minutes during a major missile attack is so daunting that U.S. policymakers gave up long ago. Today, Washington relies on the threat of retaliation to deter Russia or China from launching their long-range missiles.

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