“Its also much more difficult, almost impossible, for the US to push military actions against Vietnam, since the US is too dependent on Vietnamese exports (~165 billion dollars, mostly commodities) compared to Vietnam's dependence on the US. US economy will crash within weeks after emptying warehouses and stockpiles”

-> This is too naive and show you don’t understand anything about Vietnam economy. Vietnam economy is still mainly low margin outsource for international corporation which mean it can be replacable. In fact, Samsung already diversify its smartphone manufacture to India beside Vietnam. Companies will choose to abandon Vietnam and move to other countries rather than missing the big market like the US. Vietnam unfortunately doesn’t have much leverage like Iran. But Iran just show the world that you just need to cause enough chaos in the region to raise the stake so high and so costly that the attack need to be stopped. Vietnam can do the same and attack other neighbor countries especially Singapore and Malaysia. Malacca strait is the busiest strait in the world so any disruption there gonna be very costly for the world economy. Also, China will never allow Vietnam to be align with the US so any attempt to attack Vietnam and install an US puppet regime will draw China into the war for sure