Wars of necessity are essentially unavoidable. They involve the most important national interests, a lack of promising alternatives to the use of force, and a certain and considerable price to be paid if the status quo is allowed to stand. Examples include World War II and the Korean War.
When I grew up, in Taiwan, the Korean War was seen as a good war, where America protected Asia. It was sort of an extension of World War II. And it was, of course, the peak of the Cold War. People in Taiwan were generally proAmerican. The Korean War made Japan. And then the Vietnam War made Taiwan. There is some truth to that.
Harry Truman's decision to fire Douglas MacArthur at the height of the Korean War in April 1951 shocked the American political system and astonished the world. Much of the world didn't realize the president had the power to fire a five-star general; much of America didn't realize Truman had the nerve.