Transcript for US steps up its missile defense

Breaking developments at this hour involving the U.S. Military. For the first time the U.S. Military has intercepted a mock intercontinental ballistic missile. This test coming as North Korea appears to be closer its goal of building a missile that could reach U.S. Territory. Here's ABC's Martha Raddatz. Reporter: It was the first live-fire intercept test of an intercontinental ballistic missile in history. A critical test, at a critical time. The mock warhead, like this one used in a shorter range test in 2014, fired from an island in the pacific. More than 4000 miles away, at an airbase in California, the interceptor, or "Kill vehicle," launched from an underground silo. A little over an hour later, the Pentagon confirming the test was a success. It has been called the "Ultimate precision guidance challenge," hitting a speeding bullet with another speeding bullet. Making this test all the more remarkable. This is a very difficult calculation, you look at its arc and figure where the intercept is going to occur. Reporter: The missile intercept test was carried out after North Korea successfully launched its ninth missile this year, a short-range ballistic missile, with Kim Jong-un watching. State-run media claiming it was more precise than ever. Martha, the U.S. Of course hoping the successful intercept will now send a powerful message to Kim Jong-un. Despite this success no guarantee this will work in real-world circumstances. North Korea will remain a very big threat. David. All right, Martha on the late developments. Next tonight, new reporting

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