Since I do not serve in the US military, I don't know for sure, but I would be really surprised if it was not the case, especially for ships and planes. I'd ima

Since I do not serve in the US military, I don't know for sure, but I would be really surprised if it was not the case, especially for ships and planes. I'd imagine keys are rotated on regular basis. If you think that Russia has a reliable access to those keys, then USA military has FAR bigger issues than hypotetical spoofing. And you have not adressed the second part of my comment. Not only we haven't heard about spoofing as a reason for those incidents, but also even with civilian recievers spoofing can be detected by comparing GNSS and IMU data. And even before that you can detect anomalous power of GNSS signal (since spoofing usually has to outpowr legitimate signal) or find that there are "satellites" which produce unconsistent signals.