I would encourage you to look into a recent documentary about the congressional testimony from numerous high ranking intelligence officers - https://en.wikipedia.org/wiki/The_Age_of_Disclosure

tl;dr Of the claims they make in the documentary, the biggest thing (to me) appears to be a massive siphoning of tax dollars into black ops programs that don't report up through the government. Whether there are actual UFO/UAP programs is up to debate.