The MoD revealed that theunmanned aerial vehicle flew from a base in Italy, through southern Europe before entering UK airspace to Norway, before returning to the States.
The flights took place at heights of about 50,000 feet, well above the cruising altitude of commercial airliners, according to the MoD.
Air Vice Marshal Phil Osborn said: “It is good to see existing airspace procedures enabling the seamless integration of remotely-piloted air systems, such as the unarmed Global Hawk aircraft, within European airspace.
“This trial will have helped with the development of the Nato alliance ground surveillance system (AGS) and the future airspace integration of RPAS.”
The trial, codenamed Unified Vision, comes ahead of the Nato summit in Wales this September, where world leaders will gather to discuss issues, including terrorism, cyber attacks, and piracy.