Pentagon begins release of UFO files packed with unexplained sightings

The Pentagon has begun releasing files on unidentified aerial phenomena, including a substantial number of sightings that remain unexplained.

The documents cover military encounters recorded over several decades, with sensor data and pilot reports among the material.

Officials stress that unexplained does not mean extraterrestrial, and that many cases involve sensor artefacts, balloons or drones.

Researchers say the release is still valuable, giving outside analysts access to material that was previously classified.