The Northrop Grumman RQ-4 Global Hawk is the principal high altitude reconnaissance UAV in service with the USAF and US Navy. The RQ-4 is equipped with a suite of advanced sensors, including imagery, signals and moving target indicators and is capable of all-weather, day/night missions with exceptional endurance of over 30 hours. It is outwardly similar to the better known Predator family of UCAVs but considerably larger and powered by a Rolls-Royce turbofan engine which allows its a much heavier payload while retaining an endurance of over 30 hours. The aircraft is operated with launch and recovery as well as a mission control elements, with one pilot each as well as a sensor operator. US Navy versions are known as the Triton and have a maritime surveillance role, with strengthened wings for lower altitude flight. Despite its intention of replacing the venerable U-2, the RQ-4's operational costs as well as inferior sensors have resulted in it being purchased in smaller numbers than originally planned. RQ-4s have been used over Iraq and Afghanistan and are currently deployed globally. Numerous US allies have expressed interest in the aircraft but so far no foreign orders have been received.

The prototype was first flown on 28 February 1998 and was rushed into service as the RQ-4A in 2001. The improved RQ-4B featured increased payload and a larger wingspan at the expense of slightly reduced speed and range. US Navy units are designated MQ-4C Triton while the EQ-4B is used for communications relay. A proposed version for Germany was known as the RQ-4E Euro Hawk but was not produced.