Russia is engaging in its own pivot to Asia in the same way that the US has tried to do. But Russia is caught between its interests with China and Vietnam. With China, it's strategic because China is such a huge market for Russia. But with Vietnam you have the history.
The Soviet Union and Vietnam were allies during the war and you still have a lot of Russian investments - particularly in the oil sector and in military exports. For example almost all of Vietnam's military hardware comes from Russia or Ukraine or the former Eastern Bloc. But Russia has its own reasons to be nice to China. There's the sense that there's a tacit Russia-China understanding to try to stretch American power as much as possible by keeping it bogged down with crises in Asia and Ukraine.
"Vietnam is very worried that it might lose the support of the friendship of Russia. And it's trying very hard to stop the Russians from taking the Chinese side."
The quiet plan is to keep US playing military and diplomatic whack-a-mole all around the world so that it runs out of energy. Vietnam is very worried that it might lose the support of the friendship of Russia. And it's trying very hard to stop the Russians from taking the Chinese side. For example there's recently been a case brought by the Philippines against China about who claims the rights to the bulk of the South China Sea. China angrily condemned it and refused to recognise it. But Russia was sympathetic towards China. And this upset the Vietnamese. However it could be argued that Russia’s position was probably down to a similar case coming from Ukraine to do with Crimea. And so it may simply have been Russia protecting its own interests in Crimea rather than taking a pro Chinese line.