The Northrop Grumman RQ-4 Global Hawk is an unmanned (UAV) surveillance aircraft. It was initially designed by Ryan Aeronautical (now part of Northrop Grumman), and known as Tier II+ during development. The Global Hawk performs a similar role as the Lockheed U-2. The RQ-4 provides a broad overview and systematic surveillance using high-resolution synthetic aperture radar (SAR) and long-range electro-optical/infrared (EO/IR) sensors with long loiter times over target areas. It can survey as much as 40,000 square miles (100,000 km2) of terrain a day.
The Global Hawk is operated by the United States Air Force. It is used as a high-altitude platform covering the spectrum of intelligence collection capability to support forces in worldwide military operations. According to the United States Air Force, the superior surveillance capabilities of the aircraft allow more precise weapons targeting and better protection of friendly forces. Cost overruns led to the original plan to acquire 63 aircraft being cut to 45, and to a 2013 proposal to mothball the 21 Block 30 signals intelligence variants. Each aircraft was to cost US$60.9 million in 2001, but this had risen to $222.7 million per aircraft (including development costs) by 2013. The U.S. Navy has developed the Global Hawk into the MQ-4C Triton maritime surveillance platform.