Now I'm not saying I look forward to seeing another Sino-Vietnam conflict but IMO it's a waste of time and money protecting rocks, shores, or islands that belonged to someone else.
History is what it is...but at those time frames, the Vietnamese were not prepared or able to use what they had and it told in the outcomes.
Times have changed for both Navies that regard.
Everythig I have heard, some of it from friend in the US Navy, tells me that the Vietnamese Navy has made great strides in its professionalism and capabilities.
The vessels they are putting together could not hope to prevail against the entire PLAN fleet...but they are not meant to.
They are meant to send a message that if the PLAN wants to resort to force, the Vietnamese would make it very expensive for them.
As to who is protecting whose rocks and islands, I am sure that the same could be said against both sides by the other. IOW, the Vietnamese think that they are defending their own rocks and islands...the Chinese think that they are theirs...and that is the whole crux of the matter.
Vietnam is spending money to bolster and punctuate its interpretation and feelings about the islands they do posses...just as China is doing with those she posses.