There are more than 30 specialized defense patent agencies in China. See "National Defense Patent Agency" for details.
General agencies cannot represent national defense patents. Because the content of national defense patent involves state secrets, it is different from general patent when applying. The staff of general patent agencies are not managed according to the confidential personnel, so naturally they can't go to them and reveal state secrets.
If you are a confidential person, I suggest you go directly to the national defense patent agency to ask, so as to avoid breaking the law.