If you mean something that would be called a war then the last one was in 1979. I heard from some on the internet who had people from their family deployed that there were still smaller conflicts in the 80s.

The territorial disputes in the recent 20 years were worse than you think, soldiers died, fishing ships were sank and there were protests. However, the Vietnamese government kept it down to not lose on the economic front. The past 2-3 years the government got on better terms with other sides and got more aggressive when it comes to the islands lol.

For the alliance, I think we have a policy in national defense that says we won’t be in any military organization, so nope. There might be others that are related to economy and security which tends to be against China’s wrongdoings though.

As a Vietnamese, our government goes with a policy that is flexible, so we don’t really align with one side. China just happens to be on the border and is super powerful so the government decides that cooperating is a beneficial thing to do for our economy. Asides from that, fuck em, every single Vietnamese person don’t have a positive view about the fucking PRC and their doings in the region.