Asia's population multiplies as its economy rises. It it necessary that the US in its role as that of Britain circa 1914/1915 should put history on a leverage and prepare for the threat that China poses/will pose. Pakistan will switch allegiance when China challenges the US (whenever it is that the chicoms think they have enough power to do so). Given this, the only reliable allies that the US really has is India and Japan. Vietnam is another potential ally in countering China. This would in effect serve the US well if it would make concrete, the relationship with these 3 countries and then also concentrate on certain central Asian states like Kirghizstan, Turkmenistan and Uzbekistan (Kazakhstan's fallen to the chicoms).
Vietnam is NOT an ally. They would as soon ally with China in a war against the US, and settle their differences later.