Krugman on the Roots of War

Not an economist's area of interest, normally, but there's a tie-in.

Modern nations can’t enrich themselves by waging war. Yet wars keep happening. Why?

One answer is that leaders may not understand the arithmetic....And delusions of easy winnings still happen. It’s only a guess, but it seems likely that Vladimir Putin thought that he could overthrow Ukraine’s government, or at least seize a large chunk of its territory, on the cheap — a bit of deniable aid to the rebels, and it would fall into his lap.

And for that matter, remember when the Bush administration predicted that overthrowing Saddam and installing a new government would cost only $50 billion or $60 billion?