Starting this September, the U.S. Navy will station an Aegis destroyer in the Sea of Japan that is equipped with special software for their radar  and SM-3 anti-missile missiles. The special software  for the Aegis radar system  enables it to spot ballistic missile launches, and fire an SM-3 missile to knock down the ballistic missile. In this case, the destroyer would be monitoring North Korea. The SM-3 can destroy short and medium range ballistic missiles at very high altitudes. In effect, this (as yet unnamed) destroyer will protect South Korea and Japan from North Korean ballistic missiles. Of course, the single destroyer will not be on duty 24/7, and the North Koreans may send out warships to try and track the destroyer when it is on duty, and note when the destroyer returns to port. By 2005, the navy will have ten destroyers equipped with SM-3 missiles, and by 2006, there will be fifteen ships. Thus by next year, it would be possible to station SM-3 equipped destroyers off the coasts of North Korea and Iran, and track their ballistic missile launches around the clock.