Would it be a bigger national security threat than Chinese warships sailing into the San Francisco Bay?
A Red Chinese missile-firing sub in San Francisco Bay is no more a threat than the same sub patrolling 200 miles off the coast of San Francisco.
But, to your point of Red Chinese military bases in California: the U.S. should enforce the Monroe Doctrine.
Of course, the U.S. would have to have the political will to do so.