It's very likely a psyop like you said. "You don't know how advanced we really are! When we come for you you better just give up!"

I bet the us does have some secret weapons technologies. I wouldn't be surprised if some of them are sci fi adjacent. But I think their biggest asset is likely intelligence, and channels to mass manipulate people via the Internet and boots/agents on the ground. Fortunately for other countries that power is more effective domestically. Unfortunately for us citizens there are trillions of dollars developing technologies to destroy us and not enemies.

The shift in us politics is directly related to feeding this. Defense/offense companies need to make more money. So they need to use these tools. Us citizens are the likely next targets beyond things like software exploits and taking over a few countries seemingly randomly.