The Pentagon has released its fourth batch of declassified UFO files, with 40 records from Nasa, the CIA, the FBI and the Department of Energy. They include a 2015 lockdown at a Texas nuclear weapons plant and green fireballs debated by Manhattan Project scientists.

The volume includes 40 new files, including 19 videos.

Among the newer material, one video shows a military sensor tracking an object resembling a six-pointed star over the Yellow Sea. Any mention of ET? Not yet!

The second batch of UFO files comes just two weeks after the Trump administration released more than 160 documents.

The U.S. military released a new batch of files related to UFOs, including one report from a Navy pilot who said a mysterious object was "unlike anything I had seen" in 28 years of service.