These are not new releases, here's Reddit from a year ago people discussing them: https://old.reddit.com/r/StrangeEarth/comments/1aru95c/these...
Search for "The Amalgamated Flying Saucer Club of America", there's a lot of discussion that these photos may have been a hoax. I'm not sure why these would be just getting release by National Archives now, perhaps as a distraction?