What did WWII, the Cold War, and conflict in Korea, Vietnam, and the Middle East have in common?

What did WWII, the Cold War, and conflict in Korea, Vietnam, and the Middle East have in common?
Be sure to FULLY support your argument with historical information in a multi-paragraph essay with a minimum of 300 words (include introduction, body, and conclusion paragraphs.)
Follow English grammar standards and rules, use Times New Roman size 12 font, and double-space your essay. Include a minimum of two credible, scholarly sources (your textbook is fine, too).