Historically, wars were fought primarily for material gain: livestock, treasure, tribute, or territory. More recently, however, the profit motive for war has declined as life has become more precious and conquest and plunder have become less acceptable, although conflicts waged for control of diamonds and other precious commodities continue in parts of the world. International law generally prohibits military action by one state against another except for reasons of self-defense. In modern warfare, “gains” must be measured in less-tangible forms, such as preserving national security, liberating threatened populations from tyranny, protecting human rights. Military action to achieve such ends is considered unavoidable and is rarely assessed as an investment.
The invasion of Iraq was a war of choice, however, and therefore should be assessed in terms of costs and benefits. Neither the United States nor its allies had been attacked by Iraq, and there was no evidence that any attack was imminent. Saddam Hussein was a brutal tyrant, and his regime was an affront to human rights, but the country had suffered under his rule for many years. Iraq's liberation was not the reason for going to war. The official purpose of the invasion was to remove any threat posed by Iraq's presumed arsenal of weapons of mass destruction. Regime change was a consequence, not a cause. And although Iraq's citizens are freer now, they are by no means more pro-American.