It was not immediately clear whether the collection of videos, photos and interviews would significantly advance the public's understanding.

The Pentagon on Friday released what it says are “never-before-seen files” on UFOs after President Donald Trump directed the agency to do so earlier this year.

A new Pentagon website housing the documents on UAPs has a decidedly retro feel, with black-and-white military imagery of flying objects displayed prominently on the page, with statements displayed in...