An article in War on the Rocks debunks President Donald Trump's claim that the missile defense system protecting the United States is "97.5 percent" accurate. The system, according to missile defense experts Ankit Panda and Vipin Narang, is actually just above 50 percent accurate.

Last week on Sean Hannity's Fox News show, Trump told the TV show host, "We have missiles that can knock out a missile in the air 97 percent of the time, and if you send two of them it's gonna get knocked out." Trump was referring to Ground-based Midcourse Defense, an anti-ballistic missile killer stationed at Fort Greeley, Alaska and Vandenberg Air Force Base, California. The President brought this up, of course, in reference to North Korean dictator Kim Jong-un and reports that his country now has the ability to launch an intercontinental ballistic missile armed with a nuclear warhead at the United States.

The problem with Trump's claim? It's simply not true. Ground-based Midcourse Defense missiles have been tested eighteen times, with ten successful intercepts of a simulated incoming warhead. That's not 97.5 percent, that's only 56 percent. The United States is simply not as safe as Trump claims.

There are currently 36 GMD interceptors deployed to defend the United States. If four GMD interceptors, each with a 56 percent kill probability, were launched a single incoming North Korean missile, the probability that the missile would be shot down rises to 97 percent. (The Pentagon is believed to allocate four or five interceptors per warhead, just to be sure.) But as Panda and Narang point out, Trump's talk makes it clear he was talking about the accuracy of individual interceptors.

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AFP PHOTO/KCNA VIA KNS//Getty Images
North Korean Hwasong-14 intercontinental ballistic missile.

It's unclear where Trump got his figures. The reality is, with a 56 percent probability rate, even a modest North Korean attack has a decent chance of penetrating U.S. defenses. If North Korea were able to get ten missiles off before Trump's attack, at a rate of four interceptors per incoming missile (presuming, of course, all of them work properly), the U.S. arsenal has a 97 percent chance per missile of stopping each of the first nine missiles. Expressed another way, nine North Korean missiles (assuming they too work properly) have a three percent chance of killing hundreds of thousands or even millions of Americans.

Now, North Korea is probably not as far along at being able to strike the United States as it would like you to think. And U.S. missile defenses are not standing still in response to the North Korean threat. The U.S. is increasing the number of GMDs to 44, though at a rate of four interceptors per missiles, that only gets you to 11 missiles.

Why does this matter? Trump is the president, and if he believes the missile defense system that protects the American people is 97 percent effective, he could be emboldened to make good on his now-famous "fire and fury" threat against North Korea and its nuclear weapons. If North Korea gets missiles off before the American attack wipes out their launch locations, American lives could be jeopardized because of a false belief.

Read more at War on the Rocks

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Kyle Mizokami

Kyle Mizokami is a writer on defense and security issues and has been at Popular Mechanics since 2015. If it involves explosions or projectiles, he's generally in favor of it. Kyle’s articles have appeared at The Daily Beast, U.S. Naval Institute News, The Diplomat, Foreign Policy, Combat Aircraft Monthly, VICE News, and others. He lives in San Francisco.