So, the issue of openly courting Vietnam is a Chinese cultural thing. See, the Chinese love having buffer states and back in the Vietnam war, there was reported issues between the Russians and the Chinese over the Russians supplying North Vietnam. The Chinese didn't mind there being a North and South Vietnam, as the North could act as a buffer to the non-communist South. Same thing with Korea, really, the North's value is a buffer state. They absolutely do not want American troops in a country directly on their border like that. If you've ever wondered why Mongolia exists as a country, it's fundamentally this.
Openly connecting with Vietnam would make the Chinese flip their shit in a non-posturing way, especially since the Vietnamese basically gave them a class in "Welcome to the Jungles, motherfuckers," in 1979. I've heard Vietnam has made quiet inquires about buying military equipment from us, if America and Vietnam start openly talking about security treaties? That's when you should start firing up your Inkspot albums.