美国有线新闻 CNN 美军成功进行反导系统试验 美领导人商讨对朝策略（在线收听）

AZUZ: American leaders are discussing how to respond to North Korea's latest's weapons test. It involved a missile that flew over Japan, a U.S. ally, before landing somewhere in the Pacific Ocean on Tuesday. North Korea's government controlled media called it a, quote, meaningful prelude to containing Guam. That's a U.S. territory in the Pacific.

Meanwhile, the U.S. military ran a successful test of its own on Wednesday, when an American destroyer at sea shot down a missile that was test-fired from an American base in Hawaii. Defense Secretary James Mattis says America is never out of diplomatic solutions to international problems.

But as you're about to see, the U.S. does have a backup plan.

KYUNG LAH, CNN CORRESPONDENT: This is America's final shield, the last and only protection against an incoming North Korean nuclear missile, housed deep underground in the heart of Alaska's wilderness at Fort Greely, about 150 miles north of Fairbanks. The heavily armed 49th Missile Defense Battalion secures 38 missile silos, dotting a landscape frigid even in late summer. The tip barely revealing what lies beneath.