A U.S. high-altitude unmanned surveillance aircraft was said to have conducted a mission over the Korean Peninsula on Wednesday. 

According to Aircraft Spots, a website that monitors military air movements, a U.S. Air Force RQ-4 Global Hawk flew over the peninsula, including southern parts of Gyeonggi Province, at an altitude of 16 kilometers.

The report comes after North Korea revealed it had conducted a "very important" test at its Sohae satellite launching site. 

The RQ-4 Global Hawk is a remotely-piloted reconnaissance aircraft equipped with radars and infrared detectors that enables it to distinguish objects 30 centimeters big on the ground from an altitude of 20 kilometers. Its flight endurance ranges between 38 and 42 hours and its operational radius is three-thousand kilometers. 

The U.S. military apparently deployed the plane to identify any signs of additional tests or provocations by the North and to send a warning to Pyongyang.

Flights of the Global Hawk over the Korean Peninsula have rarely been reported.