Kim Jong-un’s goal is to survive and pass his regime on intact to a successor, presumably a yet-to-be-born son. He has relentlessly pursued this goal by assassinating would-be competitors to power in fairly creative ways, such as blasting his uncle apart with an anti-aircraft gun and having his half-brother poisoned with a nerve agent. He has learned the lesson of Saddam Hussein’s Iraq and Muammar Qaddafi’s Libya: Survival comes not from the barrel of a gun, but from a nuclear-tipped missile capable of killing hundreds of thousands of people, preferably Americans, with the push of a button. As a charter member of the “Axis of Evil,” Kim Jong-un understands all too well that regime change is only a moment away. To avert this unwanted future he holds South Korean, Japanese, and soon American cities hostage with hundreds of artillery tubes and now missile-delivered hydrogen bombs.

Kim Jong-un is not stupid or suicidal. Absent an existential threat he will hold his fire, provoking his enemies with missile and nuclear tests but not providing them a casus belli. He may miscalculate and cross an unseen Trump administration red line, but not purposefully. He knows that war means the end of his regime and perhaps as well the extinction of the North Korean people.

Two-thirds of the American public opposes launching a preventive strike against North Korea, and world opinion is overwhelmingly opposed. If it were to strike North Korea without sufficient provocation, the Trump administration would sacrifice public support and international goodwill, much as the Bush administration did by invading Iraq without international backing in 2003. A first strike may not succeed in destroying all of North Korea’s missiles or nuclear weapons, even one of which could wipe out Seoul, Tokyo, or Seattle. A preventive strike would be the proverbial roll of the iron dice, resulting in uncertain outcomes and unintended consequences.

Fortunately, the U.S. national missile defense system, composed of ground-based interceptors based in Alaska and California, the ship-based Aegis ballistic missile defense system, the theater-based Terminal High Altitude Area Defense system based in South Korea and Guam, and shorter range anti-ballistic missile systems such as the Patriot PAC-3, will in time grow to the point where it can reliably intercept North Korean missiles headed for U.S. and allied territory. Despite criticism that ground-based interceptors have succeeded in only 9 of 17 tests since 1999, the most recent test of the system this year was successful. As the technology matures, the reliability of the system will improve, and with it the ability of the United States and its allies to defend against a North Korean missile attack.

As for the threat of a conventional artillery bombardment of Seoul, the South Korean government should take a page out of Israel’s playbook and develop an “Iron Dome” system to protect the capital. Effective defenses will give the United States and South Korea the latitude to wait for Kim Jong-un to fire the first shot in any conflict. Missile and artillery defenses can parry the blow, positioning the United States and its allies, with international backing, to consign Kim Jong-un and his regime to the dustbin of history.

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