Redmond’s previous system relied on digital escorts — American employees with proper security clearances — to monitor the foreign engineers working on the systems. However, it’s been noted that some of these U.S. citizens weren’t knowledgeable enough to determine if the person they were monitoring was doing regular work or putting in a backdoor.
This is a problem all over the FedGov. I've been on both sides of this situation. I've been a contractor escorted into spaces I was not cleared to be in. And, I've escorted contractors in cleared spaces. I can kinda see how the situation developed. When I was a contractor being escorted, the folks escorting me were great folks, but most knew fuck all about computers. I could have been up to some pretty shady stuff, and they likely would not have recognized it. Also, as physical escorts who were comfortable with me, they weren't exactly monitoring the screens all that closely. Even when it was me escorting contractors, I wasn't always completely knowledgeable about their work. Sure, I might know more about computers than some folks, but I don't know everything about everything, and it's possible that they could have slipped one past me.
All that said, when I was doing this stuff, I was subject to background checks on the regular. While they didn't quite go to the level of stuffing a microscope up my arse, I wouldn't have been surprised if they asked about it. So, how the fuck did Microsoft end up with Chinese nationals working on DoD systems? While I'm sure there's some great IT folks over there who just do their jobs and wouldn't get involved in spying/sabotage, this is just plain stupid. We're putting systems for our military in the hands of folks under the direct influence of once of the US's main adversaries.