That's very interesting heiss93, I had no idea it was that bad. It's incredibly tragic that Vietnam has been moving in the direction of the US, less than half a century after being bombed into the stone age by them. But I understand the geopolitical bind they're in, too, since the USSR's not around anymore and they have that ongoing dispute in the South China Sea with the Chinese where, frankly, I think Beijing's claims are utterly unreasonable.
Actually Vietnam's problems (and search for alternative partners) started in early 1988, when, just weeks after Gorbachev announced a reduction in troop deployments on the Chinese border and a withdrawal from Afghanistan, China and Vietnam fought it out for the Johnson South Reef and Hanoi lost. Actually, in the Vietnamese-language article on that incident (which is quite thorough and pretty neutral), the USSR's traitorous behaviour is mentioned in some detail, including 1) the lack of broad condemnation of China's occupation of the islands, despite the Vietnamese ambassador's request to do so, 2) the non-intervention or mobilization of Soviet naval forces, 3) and Vietnam's subsequent move away from Moscow toward 'multilateralization' of its foreign policy.
https://vi.wikipedia.org/wiki/Xung_%C4% ... ng_Sa_1988