"Hitting a bullet with a bullet" aptly describes the challenge of destroying incoming missiles, but effective defence does exist.
North Korea threats have led the Obama administration to discuss deployment in South Korea of the Lockheed Martin THAAD (Terminal High Altitude Air Defence) anti-missile system.
Earlier, the Pentagon expanded anti-ballistic missile (ABM) defence on the United States west coast, and sent the system to Guam.
In 2009, THAAD was sent to Hawaii during earlier threats by North Korea.
A somewhat comparable missile confrontation occurred during the final months in office of President George W. Bush.
Plans were announced to deploy anti-ballistic missiles in Poland, with associated radar installations in the Czech Republic.
In the fall of 2009, the new Obama administration announced the US would rely instead on a mobile sea-based system, with land-based mobile radars.
Conservative critics instantly charged this was appeasement.
In fact, President Obama made a good call. Sea-based weapons are more secure as well as less provocative.
Debate over the best balance of defensive and offensive military capabilities is as old as warfare.
Technology complicates, but does not abolish, this dual reality.
Long-term military-industrial pressure to develop missile defenses, plus a vast array of other capabilities, dates back to the Eisenhower administration.
Pentagon spending then absorbed much more of the total federal budget.
Ike maintained control over the military primarily, though not exclusively, by putting a ceiling on the total defense budget, effectively forcing the Air Force, Army and Navy to compete for available resources.
One byproduct was considerable duplication of effort.
Each service developed a separate strategic missile program, jealously guarding research and development.
New Kennedy administration Defence Secretary Robert McNamara was instantly offended by the lack of formal logic in this approach, and immediately imposed organisation-chart order.
The Air Force was given land-based strategic missiles, the Navy sea-based submarine systems, and the Army was removed from the game.
The secretary and his academic analysts also rejected arguments for anti-ballistic missile systems, because any conceivable defence could be overwhelmed at relatively low cost by simply increasing the number of attack vehicles.
Priority was given to protecting military sites.
If we were planning a nuclear Pearl Harbor, there was no point in protecting missile launchers that would be empty.
The Soviets never accepted this complicated perspective.
Domineering Secretary McNamara quickly unified the services against him.
As the Vietnam War grew, he lost control and was short-circuited by the military.
He became isolated, and emotionally troubled.
Meanwhile, the Army pressed successfully for an ABM role.
President Lyndon Johnson generously named McNamara president of the World Bank, but demanded public support for ABM. Johnson by then was in desperate political trouble.
In the 1980s, President Ronald Reagan gave priority to space-based missile interceptors termed the Strategic Defense Initiative or "Star Wars."
The Air Force became the leading service but the entire Joint Chiefs of Staff endorsed the effort, with Reagan and Defence Secretary Caspar Weinberger prime exponents.
Nuclear strategist Herman Kahn used the potential threat of a rogue regime to defend publicly McNamara's forced support of the ABM.
North Korea represents precisely the threat Kahn had in mind.
China has warned for a long time that THAAD in South Korea would be a grave provocation.
Secretary of State John Kerry has an opportunity to leverage Beijing to restrain North Korea as the price of not deploying this anti-missile system.
Diplomacy is key, today as through history.
Arthur I. Cyr is Clausen Distinguished Professor at Carthage College and author of "After the Cold War".