The U.S. Department of Homeland Security tracks the locations of naval vessels of 300 gross tons or larger that are bound for U.S. ports or that are within 1,000 nautical miles of the U.S. coast. The Department of Homeland Security only tracks vessels from International Maritime Organization member states.
The U.S. vessel tracking system is known as the Long Range Identification and Tracking system, or LRIT. The system employs satellite-based tracking to allow operators to locate vessels in real time. LRIT complements other naval vessel tracking systems employed by the U.S. government and military, many of which are considered classified.