The grandson's claim, made in a letter to defense officials in 1999, is one of many matters covered in documents to be released Thursday, The Independent reported. The man, who has not been identified publicly, said his grandfather witnessed Churchill and Dwight D. Eisenhower, then the supreme commander of allied forces in Europe, discussing UFOs.
Churchill reacted strongly to a report that a Royal Air Force bombing crew returning from a raid on Germany saw an arrow-shaped object hovering above the plane, the report said.
"This event should be immediately classified since it would create mass panic amongst the general population and destroy one's belief in the Church," the iconic prime minister said.
Both British and U.S. air crews frequently spotted what they called "foo fighters," a name taken from a comic strip. Scientists say most or all supposed UFOs can be explained as natural or man-made phenomena, including weather balloons and unusual cloud formations, or as some combination of stress and imagination.
Notable deaths of 2014 [PHOTOS]