One of US policitcs' most powerful tools for distracting citizens from the problems in their own country, with the added bonus of a massive economic boost and the spoils of victory (if the war ever ends). Find some evidence that something is happening in another country that you don't like (or make it up, if you have the balls/ignorance), then send in a massive invasion force with little planning and watch the inevitable shit-storm. If you lucky, your war could go on for years, where not too many people die; just enough for people to keep arguing over the issue will keeping most of the armed forces relatively safe. And, if you get really luck, you might end up fighting a seemingly endless number of determined guerilla fighters that can be used as an excuse to keep troops there indefinitely, all the while making more and more money from the sale of arms to fund the never ending cycle. Unfortunately, your war will likely end at some point. No matter, after a year of so, simply rinse and repeat.
War in Iraq
Wat in Afghanistan