From The Christian Science Monitor:
The missile defense system deployed in Kauai in response to North Korea worries has been tested successfully several times, but never in combat.
Washington - A missile defense system yet to be tested in battle could be thrust to the forefront to protect US soil amid concerns that North Korea may be preparing a missile strike that could hit Hawaii.
An unconfirmed Japanese media report said recently that Pyongyang was considering a test-fire of its Taepodong-2 ballistic missile in early July that could be within range of the Hawaiian islands. Defense Secretary Robert Gates says the Pentagon is watching the situation "very closely" and is confident of being able to shoot down anything lobbed toward the US.
Read more ....
Update: Pentagon Deploys Experimental Missile Shield to Hawaii -- The Danger Room
My Comment: The North Koreans are not going to target Hawaii .... to do so would be an act of war. The last time such an event occurred (Pearl Harbor, 1941), the Japanese learned the hard way that there are consequences and repercussions .... a fact that I am sure the North Koreans are more than aware of.