There's no dissident in US. That country allows different thoughts and ideas. Yes, CIA did something tough against those intellegent guys, those spies. CIA regards foreign spies as who threat US national security.
The difference is: How does China gov define the word "national security"? Do you think simply say something , or publish something against the gov, or mailing some magazine with democratic idea, means threating China's security?
How tender the China's security is! No, it's not of China, it's of CPP only.