India, Oct. 23 -- Newly declassified government documents on UFOs revealed Friday that mysterious black triangle-shaped objects have been spotted moving at speeds up to 1,800 miles per hour without leaving vapor trails over classified US military installations. These sightings occurred on at least three different occasions throughout the past year.

These sightings have raised serious national security worries, and according to redacted files on unidentified anomalous phenomena released Friday by the Trump Administration, officials still haven't determined whether these objects originated from foreign nations or elsewhere.

The triangle sightings sparked worry for two key reasons: the cutting-edge technology they seemed to display and the...