America Has a Commitment Problem

Do Americans agree about anything anymore? Well, yes. Apart from a handful of unrepentant neoconservatives and reflexive warmongers (including, alas, the present national security advisor), I think there's a growing consensus that the United States is overextended. We’re still fighting at least two wars (while conducting a whole bunch of more-or-less clandestine operations against various extremists in various places), and we are formally committed by treaty to defending more countries than at any time in U.S. history. There is little or no consensus on how to deal with this situation, but even those who think U.S. global leadership is the only thing preserving the world from barbarism might concede the need for a bit of readjustment these days.

Which raises an interesting question: How did this happen? How do states get overextended? If the world is highly competitive and it's important to set priorities and focus on the big challenges, then why would any country take on commitments that were of secondary importance or beyond its means? And if it did, why would it hang onto them after it was clear that the costs far outweighed the benefits?...