A US military transport aircraft was spotted in Japan on Thursday as tensions with China and Russia continue to escalate.

Flight tracking data shows a US Boeing C-40 Clipper stationed at Naval Air Facility Atsugi, the largest US Navy base in the Pacific, briefly departed the base at 5.21am ET before returning after just over three minutes.

Aviation observers noted the unusually short flight, sparking questions about its purpose.

Read more: Mystery US military jet makes three-minute flight in Japan as tensions escalate with China and Russia