Tonight, the united states is bolstering its missile defense on the west coast by nearly 50%. Abc's chief global affairs correspondent martha raddatz tells us just how real this threat is. Reporter:... See More
Tonight, the united states is bolstering its missile defense on the west coast by nearly 50%. Abc's chief global affairs correspondent martha raddatz tells us just how real this threat is. Reporter: Today, more provocation, two short-range missiles launched. But it is the unexpectedly quick advances that north korea and its young leader, kim jong-un, have made in recent months, the nuclear tests, the long-range missile launches, and this apparently new road mobile intercontinental ballistic missile that has convinced the pentagon that protective measures must be dramatically increased. The reason we're advancing our program here for homeland security is to not take any chances, is to stay ahead of the threat. Reporter: There will be 14 new missile interceptors added to the 30 already deployed. The interceptors are designed to detect a launch with satellites and radars. If an enemy launch is detected, dozens of interceptors can be fired from california and alaska. This young lad ought to be deterred by that. Reporter: And the pentagon made clear today that north korea's mobile icbm has the range to reach the u.S. While those interaccept torps can track and destroy enemy missiles long before they hit their target, the system is far from foolproof. We've never had a test against the kinds of missiles that north korea would shoot at us. The only way we're going to find out is a real world scenario. Reporter: Officials at the pentagon acknowledge there have been mixed results in some of the tests on the interaccept torps, but secretary hagel said today, we have confidence in our system.
This transcript has been automatically generated and may not be 100% accurate.