China's increasingly aggressive maritime manoeuvres in the South China Sea, not only against Vietnam but also Taiwan, the Philippines and Malaysia, is pushing the communist government in Hanoi closer to its former rival the United States.
Vietnam has been involved in a decades-long territorial dispute with Beijing over islands in the South China Sea which both countries claim are theirs.
However China has built infrastructure on the Paracel Islands and, given its great power, it is unlikely Vietnam will be able to coerce Beijing into giving them up.
Now Hanoi is elevating the United States to its highest diplomatic status, despite the Cold War era war both countries fought that ended in 1975.
Only China, Russia, India and South Korea also have the status of being in a "comprehensive strategic partnership" with Vietnam.
Biden appeared tired and slightly confused as he held a news conference later, raising questions about whether his age - he's 80 years old which makes him the oldest president in US history - may be starting to show.
Deepening greater economic ties is important too. As the US seeks to diversity its supply chain-reliance, and not rely so much on China, Vietnam has become increasingly economically attractive.
It's a major importer to the US and only lags behind Mexico, Canada, China, Germany, Japan and South Korea – according to the U.S. Department of Commerce.
This also happened in just 28 years as Hanoi and Washington only restored relations in 1995.