As usual, Tom Friedman of the New York Times says it better than I ever could:
The notion that Spain can separate itself from Al Qaeda’s onslaught on Western civilization by pulling its troops from Iraq is a fantasy. Bin Laden has said that Spain was once Muslim and he wants it restored that way. As a friend in Cairo e-mailed me, a Spanish pullout from Iraq would only bring to mind Churchill’s remark after Chamberlain returned from signing the Munich pact with Hitler: “You were given the choice between war and dishonor. You chose dishonor and you will have war.”