> Or you are assuming vastly more advanced technologies possessed by Chinese government.
> From what we know from Chinese tech company and track record, I doubt this is true.
It is not technically feasible, but legal consequences serve as sufficient deterrent. Not many people in the US would carry similar activities. It helps that just about all Chinese corporations are really state enterprises. It looked like state intervention might eventually disappear while Hu was in power, but under Xi, the CCP has gotten much more involved. No Chinese corporation will continue to steal US intellectual property if the party instructs them not to.
As for technical feasibility, if any country has the capability to detect those intrusions, it's China. All internet traffic in China passes through a government filter, and you're only allowed to move encrypted data if you're small fish and the CCP doesn't feel at all concerned about what you're doing. So they can monitor internet traffic better than any other state.
The hacks you hear about are not super advanced wizardry. It's mundane script kiddie stuff but with hundreds if not thousands of people behind it dedicating their full day to it. Our networks are full of security holes.
> They have all the benefit to lie about it: [...]
I concede those are pretty good reasons, but they would unravel sooner or later if there were no truth to them. It is true that this creates fear, that the US is trying to maintain high ground, that this keeps the IC budget growing. But that does not mean China is not hacking into American businesses. I assure you that China would have been much more indignant in fighting the charge if there were no substance to the IC claims.
What I would like you to consider is this: why would China not steal US secrets? Their economy is modernising, and this is exactly the kind of thing they need to speed that modernisation. This is not unique to China, by the way. Every young economy breaks the rules before it joins "The First World". See China's fight to keep its classification as a developing market, their currency manipulation, and how China is setting up shop in any place they can to avoid tariffs, quotas and other import restrictions. Hacking into American (and Canadian and European) businesses is not a wild suggestion -- what would be mysterious is China not hacking Western businesses.
> Links?
It's quite easy to find the stuff I mentioned earlier using a search engine.