Japan has put a missile detection radar into operation in the northern part of the country. The "X-Band Radar" is similar to the systems used in Aegis anti-aircraft system for ships. This technology uses thousands of small radar transmitters to get detailed information on objects out there, and many objects at once. The missile detection radar has, in addition, the ability to see activity at long distances (in some cases, up to 5,000 kilometers out.) Japan began planning their missile detection radar in the late 1990s, after North Korea test fired a long range missile that could reach anywhere in Japan. The missile detection radar can not only see a missile being launched, but it can tell the difference between decoys, and real warheads, after the missile has exited the atmosphere and sent its payload plunging back to earth. The Japanese radar was built specifically to keep an eye on North Korean missile launches.