I think it’s a mix of genuine concern about presrving sovereignty (or i guess you could call it pride) and the government’s fear of being accused of or seen as being a proxy or a vassal

I think here it’s more of an alignment issue, which is, IMO, rooted in economic coercion by the US for decades. By the time China became a major power Viet Nam was already very dependent on US imports. Corruption is a massive problem, too. Capitalism thrives in corruption and our soil very is fertile.