Before the war, many observers believed the US and its allies could win but might suffer substantial casualties (certainly more than any conflict since Vietnam), and that the tank battles across the harsh desert might rival those of North Africa during World War II. After nearly 50 years of proxy wars, and constant fears of another war in Europe between NATO and the Warsaw Pact, some thought the Persian Gulf War might finally answer the question of which military philosophy would have reigned supreme. Iraqi forces were battle-hardened after 8 years of war with Iran, and they were well equipped with late model Soviet tanks and jet fighters, but the antiaircraft weapons were crippled; in comparison, the US had no large-scale combat experience since its withdrawal from Vietnam nearly 20 years earlier, and major changes in US doctrine, equipment and technology since then had never been tested under fire.

Answer this question, if possible (if impossible, reply "unanswerable"): Prior to the Persian Gulf War, where and when was the last major American military conflict?
Vietnam nearly 20 years earlier