1) there is also a Vietnamese War! The "Vietnamese Civil War" is a part of the Vietnam War: "2,300,000–3,800,000 - Vietnam War (entire war 1945–1975) 300,000–1,300,000 - First Indochina War (1945–1954) 100,000–300,000 - Vietnamese Civil War (1954–1960) 1,750,000–2,100,000 - American phase (1960–1973) 170,000 - Final phase (1973–1975) 175,000–1,150,000 - Secret War (1962–1975) " (the numbers at the left are deaths of civilians from diseases, famine, etc. as well as deaths of soldiers in battle) Source: http://en.wikipedia.org/wiki/Wars 2) A reason could be the name of the war in the respective native language: - the Korean War: "In South Korea, the war is often called 6·25 or 6·25 War (Korean: 6·25 전쟁), from the date of the start of the conflict or, more formally, Hanguk Jeonjaeng (Korean: 한국전쟁, literally “Korean War”). In North Korea, while commonly known as the Korean War, it is formally called the Fatherland Liberation War (조국해방전쟁). In the United States, the conflict was officially termed a police action — the Korean Conflict — rather than a war, largely in order to avoid the necessity of a declaration of war by the U.S. Congress." Well, "한국" means also Korea in Korean... Source: http://en.wikipedia.org/wiki/Korean_War - the Vietnam War: "It has been variously called the Second Indochina War, the Vietnam Conflict, the Vietnam War, and, in Vietnamese, Chiến tranh Việt Nam (The Vietnam War) or Kháng chiến chống Mỹ (Resistance War against America)." Source: http://en.wikipedia.org/wiki/Vietnam_War 3) last, but not least, it just sounds better, I think. So, high phonaesthetics! http://en.wikipedia.org/wiki/Euphony

Vietnamese call it "The American War".

1. Americans are stupid 2. Neither war of them was a war, they were both "Police Actions" - ha ha

Pure ease of pronunciation. Korea War has an uncomfortable transition in the middle of it from -ea to w-. It is simply easier to say if you put the n in the middle.