THIS! My brother works for a large corp that does a lot of government(and private) work. A few years back, they tightened up their security with live monitoring, and as soon as it was enabled they realized that folks from China were actively connected. FBI was involved, but it never made the news. 2-3 more attempts have been made since. While they have an idea how long they had been breached, they don't know for sure...
I assume you rather meant 'connections originating from IP addresses owned by Chinese companies'? It's trivial to use IP address from any place in the world, regardless of your actual location.
I mean from China. It was investigated and pretty conclusively linked. Is there a chance that it wasn't China? sure. But there were specific reasons that China would want to know what this company was working on, and it was more than just an IP address cross reference that pointed to them. Now don't conflate this as "US=good, China=bad" that isn't what Im saying here. Im saying that Chinese state sponsored hackers accessed their computer systems, with reasonably credible evidence.
