That's not really comparable. Southeast Asia was an area of high population density engaged in a series of real and very deeply motivated civil wars. Vietnam (Cambodia too) was tearing itself apart entirely separate from the fact that global superpowers decided to use the nation as a proxy war.
This is a dispute over an almost empty tract of land motivated by local politics in its neighbors (and potentially also over oil wealth, something that is new to Guyana in the last few years). Most likely nothing happens, but if it does the only larger power that's going to care much is Brazil. The US is more than capable of defending the relevant oil rights whether or not Guyana controls its western jungle.
This is a dispute over an almost empty tract of land motivated by local politics in its neighbors (and potentially also over oil wealth, something that is new to Guyana in the last few years). Most likely nothing happens, but if it does the only larger power that's going to care much is Brazil. The US is more than capable of defending the relevant oil rights whether or not Guyana controls its western jungle.