Or we've paid off some Russians and know more about the S-400 and how it works than their technicians do.
“It’s apparent Russia turned off their S400 systems”
It’s possible the S-400s were jammed. It’s also possible that the US informed Russia through backchannels that if the S-400s went into targeting mode, they’d be destroyed. Finally, SAM systems can only shoot at things they can illuminate with their radar, and cruise missiles fly very low to avoid that very thing.
I will say that the US should be developing a cheap, stealthy cruise missile using modern technology.
Or we've paid off some Russians and know more about the S-400 and how it works than their technicians do.