China didn't invade vietnam in the 1970s, the US did. This is the easiest history question how did you get it wrong.
As far as the rest of your misinterpretation of history based on a radiofreeasia fantasy George HW Bush himself would be jealous he couldn't come up with in his time at the CIA; Taiwan is literally the imperial government China rebelled against. They lost the war. They are not a separate country, and no country on earth suggests they are a separate country, they are just the last holdouts from a fascist government. They didn't even have elections until the 1990s, and that was because the US threatened to stop economically supporting them. Vietnam isn't hostile to China or vice versa, in fact they have a railway planned to increase overland trade. Yes some Vietnamese vessels I'm sure have violated China's sovereignty. And like the US with boats from Mexico, they have been interdicted under international law.
Same with the fascists in the Philipines who were capturing Chinese fishing vessels under the Duterte regime and killing Chinese citizens summarily for their 'war on drugs.' Recent interdictions have been philipino vessels in Chinese waters or coming too close to chinese vessels. Given the very recent history from the regime of the internationally recognized terrorist regime Duterte, you can understand why they don't fuck around, right?