The U.S. has been concerned for decades about the threat of
a missile attack from North Korea, spending billions trying to
create a missile shield.
But it's far from ready and more on that now from our national security
correspondent, Jonathan Karl.
It was Ronald Reagan who came up with the idea of Star Wars,
a missile defense system during the height of the Cold War.
Two decades and 95 billion dollars have bought a much smaller system
that is just now taking shape. The first piece: detection.
The U.S now has radar systems around the world,
from Alaska's remote Shemya Island to this floating platform
off Japan's northern coast, and space-based infrared sensors.
The system allowed U.S. officials to track North Korea's missiles
from the moment of takeoff.