A new Unacknowledged Special Access Program (USAP) codenamed IMMACULATE CONSTELLATION has been named in a report given Congress. Apparently it was created in 2017 after the NYT article about AATIP, the "informal Pentagon UAP program."
It's goal was to consolidate UAP observations by "tasked and untasked platforms," and they seem to have collected data starting beginning in 1991:
“From 1991 to 2022, the most common UAP shapes reported in this USG dataset were spheres/orbs, discs/saucers, ovals/tic-tacs, triangles, boomerang/arrowhead, and irregular/organic.”
Shellenberger also suggests that AARO, the Pentagon's current investigatory office taking on UAP reporting, could be a continuation of the US Government's UAP public relations, rather than its actual UAP investigations, which began in the early 50's.