Pearl Harbor Two?

Can you believe that North Korea is threatening to launch a missile towards Hawaii around July 4th?

According to the WASHINGTON -- The U.S. is moving ground-to-air missile defenses to Hawaii as tensions escalate between Washington and Pyongyang over North Korea's recent moves to restart its nuclear-weapon program and resume test-firing long-range missiles. Defense Secretary Gates told reporters that the U.S. is positioning a sophisticated floating radar array in the ocean around Hawaii to track an incoming missile. The U.S. is also deploying missile-defense weapons to Hawaii that would theoretically be capable of shooting down a North Korean missile, should such an order be given, he said..

My question is this: Why haven't these ground-to-air missile defenses and radars been around Hawaii since right after 1941? Did somebody forget about Pearl Harbor?

"Those who don't remember history are doomed to repeat it.". . .author unknown