The writer, president emeritus of the Council on Foreign Relations, is the author of ‘War of Necessity, War of Choice’
Wars tend to fall into one of two categories, either necessity or choice. Wars of necessity involve the most vital national interests and require the use of military force after other policy choices (including inaction) are deemed inadequate. By contrast, wars of choice tend to involve less than vital interests and are fought even though other policies — including diplomacy, sanctions, covert action and deterrence — could arguably have been employed.
Wars of necessity include Ukraine’s response to Russian aggression in 2022. The US intervention following North Korea’s invasion of South Korea in 1950, as well as Washington’s response to Iraq’s 1990 conquest of Kuwait, were necessary. Ousting the Taliban in Afghanistan after 9/11 also qualifies, given the possibility the Taliban would have allowed future terrorism to emanate from its territory. Wars of choice are not per se a mistake. But they do place great pressure on leaders to demonstrate results that justify their decisions and the inevitable costs. Vietnam and America’s 2003 war in Iraq were wars of choice. So was Russia’s invasion of Ukraine. The current war against Iran is a textbook war of choice.