Pres. Obama called the Afghanistan campaign a "war of necessity," and the NATO Secretary-General has now echoed this formulation.
If "necessity" is set in opposition to "choice," as it was in Obama's original statement, the dichotomy is misleading. As others have pointed out, every war involves a choice. Even World War II -- properly held up as a model of a justified, inescapable war and one in which the definition of victory and defeat was far clearer and more obvious than it is today in Afghanistan -- was a war of choice. We can all be grateful that Britain in 1940 acted as she did, but it was still a matter of choice. There is, strictly speaking, no such thing as "a war of necessity." The phrase is not helpful.