Project Grudge was a short-lived 1949 U.S. Air Force program that evaluated UFO sightings during the early Cold War. It succeeded Project Sign and was the direct precursor to Project Blue Book.
Per Newsweek coverage of pursue Release 02 (src-newsweek-pursue-release-02-2026-05), Project Grudge absorbed the 209-report 1948–1950 Sandia, NM green-orb / disc / fireball cluster reported by the U.S. Air Force and the armed-forces-special-weapons-project — making Grudge a documented institutional consumer of the densest known early UAP–nuclear-enterprise cluster.