Just thinking of this after looking at the recent Border Clash between North and South Vietnam on TV. The Da Nang line has been the most fortified land AND naval border in human history, home to countless mines and traps separating the Democratic Republic of Vietnam at the South from the Socialist Republic of Vietnam at the North. Being one of the last vestiges of the Cold War Era that endures until the Present Day.
All while looking at the technically still-a-communist Democratic Republic of Korea, still under the same Kim Dynasty since the time when Communists overrun the US-backed Republic of Korea during the Korean War, but at least the Kims have been pretty competent dictators that they managed to grip on their power even after the fall of Soviet Union.
...
Say, what if the Korean War and the Vietnam War ended up differently? Like Communist North Vietnam managed to unify entire Vietnam while the North Koreans ended up in a stalemate with the South Koreans?
What would be the effect of this on world politics?