Yes. Is there any reason why US intelligence services wouldn't want a backdoor at that level? They are technically feasible, they promise to offer access that's

Yes. Is there any reason why US intelligence services wouldn't want a backdoor at that level? They are technically feasible, they promise to offer access that's difficult to detect and difficult to thwart. So there's an obvious incentive there. What are the downsides? Well, for one thing, it might be illegal. Is it? Merely installing a backdoor could be illegal, but I sort of doubt it is. The hardware company might be compliant, or the backdoor could be installed covertly. That might make a difference. And of course making use of the backdoor could be illegal. US citizens or other people on US soil might enjoy (various degrees of) protection against activities. But I get the impression that the rest of the world is pretty much fair game for US services. The fact that US citizens are protected is brought up again and again in such discussion and doesn't inspire me with a lot of confidence.