U.S. Government UFO Document: 

“SUBJECT: Reporting of Information 
on Unconventional Aircraft”

by C. P. Cabell, Major General, 
USAF Director of Intelligence,

Office of Deputy Chief of Staff, Operations, 
12 January 1950
(United States Air Force, Washington, D.C.)

(Project Blue Book Archive)

The letter by Major General Charles P. Cabell was sent to the following persons: Commanding Generals, Major Air Commands, Z. I. and Overseas; All United States Air Attaches:

http://www.bluebookarchive.org/page.aspx?PageCode=NARA-PBB89-381

Quote from the document:

“2. In the future any information obtained on this subject should be accorded the same consideration as that given to intelligence information on other subjects.

BY COMMAND OF THE CHIEF OF STAFF: C. P. Cabell (sig)”

Cabell later became a full general.

(ufocasebook.com image)