North Korea has launched 15 missile tests this year. But not one has been shot down. The Department of Defense says it can do it. But Military experts say it won’t be easy.

The Pentagon says it's like hitting a bullet with another bullet only from from hundreds of miles away.

Here's the doomsday scenario. North Korea fires an intercontinental missile. We fire one of our missiles to intercept it. As the North Korean missile starts its decent, the two collide and blow up.

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The system is called THAAD. The Pentagon has been testing publicly all summer. Our missiles have launched from places like Alaska and California. The fear is Kim's rockets could reach the west coast and beyond. Military experts say that's because Kim's missiles reach high altitudes: 475 miles up.

Experts think our missiles could only catch up late after launch when the missile is on its down-swing. They stress we can't miss because that low, there would only be one shot.