The only workable deterrent is the threat of a proportional (or more than proportional) response.
Since hacking is usually hard to pin down definitively to a single actor, and it's difficult to justify a conventional armed response, you probably want a response that has similar properties.
If you assume that China is the perpetrator, then the best response to hacking attacks is to let it be known to the Chinese government that any hacking attempts will be responded to by attempts to destabilize communist party control (encouraging dissidents through side-channels, developing/distributing tech to bypass the great firewall, etc)
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The only workable deterrent is the threat of a proportional (or more than proportional) response.
Since hacking is usually hard to pin down definitively to a single actor, and it's difficult to justify a conventional armed response, you probably want a response that has similar properties.
If you assume that China is the perpetrator, then the best response to hacking attacks is to let it be known to the Chinese government that any hacking attempts will be responded to by attempts to destabilize communist party control (encouraging dissidents through side-channels, developing/distributing tech to bypass the great firewall, etc)