The point of the matter, which i'm tying to stress, is that Vietnam's naval doctrine is purely defensive. Their land based batteries of anti ship missiles will be in itself a factor to prevent the PLAN from mobilizing to deep into the coast of Viet Nam. A ground offensive by the PLA would be met head on by the PAV. In their northern provinces, is the 1st and 2nd army region, each region is home to about 100,000. So the 1st and 2nd army region is home to the 1st and 2nd armies of the PAV, which combined is 200,000. They also have another 150,000 composed of the Border Command Guard. Combined in the northern vicinity they have 350,000 ready to respond to an invasion by the PLA.
Mind you the PAV have 3 other additional armies. That's another additional 300,000.