Last year’s gargantuan $2.3 trillion appropriations bill did a couple of very obvious things: It provided millions of Americans badly needed coronavirus relief aid and it averted an impending government shutdown. It also dealt with … UFOs. The legislation, which President Donald Trump signed into law, was a bureaucratic nesting doll that ran more than 5,500 pages and contained the Intelligence Authorization Act for Fiscal Year 2021, which itself carried an unusual provision in its “committee comment” section, beneath the understated heading “Advanced Aerial Threats.” The stipulation mandates that the director of national intelligence work with the secretary of defense...