Chinese government have deliberately developed global dominance in rare earths refining knowing that it is a strategic supply chain. They threatened to withhold supply to Japan more than a decade ago and now are withholding supply to all western nations who without that supply cannot manufacture many of the high tech and military products. My understanding is Vietnam has long been wary of China as for thousands of years China has exerted influence/expected tribute over/from neighbouring countries, and is now doing the same again. Already N.Korea, Cambodia, Laos and Myanmar are tribute states largely subservient to China. China is building a massive canal and port project in Cambodia to divert traffic on the Mekong to avoid Vietnams strategic control of the Mekong delta. It is also building road and rail through Myanmar to access international shipping routes avoiding the Malacca strait.