> China/Russia/whoever
As a placeholder for potential US adversaries who might have the motivation do something like this. If you don't like that I said Russia, ignore it and fill it in with China.
https://www.airandspaceforces.com/china-air-force-may-take-a...
If you think people are seeing real flying saucers that are defying the laws of physics, I don't know what to tell you.
>China/Russia/whoever can send whatever they want into US airspace and there's nothing that anyone, including the military, can do about it.
So it's not "whatever they want", it's cheap drones and balloons. You make China out to be some scary powerful Boogeyman (which requires the USG to invent alien stories as a cover) and then admit they don't have such capability.
I personally am not scared one iota about Chinese aircraft threatening US airspace. And I am very confident that if such a scenario did arise, the US military would address it in the most appropriate and effective way. Which could range anywhere from ignoring it, to neutralizing with extreme prejudice.
However, if people think they're aliens, that instead turns psychological warfare on its head and into something that inspires awe, wonder and possibility. No one is scared in the ways adversaries want them to be scared, and no one doubts the government is actually capable of handling threats from adversaries.
"Aliens" as an explanation quells the potential for panic, versus adversaries successfully inducing the panic responses they desire. It also gives the opportunity for those who care too much about this to be painted as quacks.