[S]o it seems that Turkey wasn't really haggling about the price, it just wouldn't accept payment by check or credit card. In return for support of an Iraq invasion, Turkey wanted ? and got ? immediate aid, cash on the barrelhead, rather than mere assurances about future help. You'd almost think President Bush had a credibility problem.

And he does.

The funny thing is that this administration sets great store by credibility. As the justifications for invading Iraq come and go -- Saddam is developing nuclear weapons; no, but he's in league with Osama; no, but he's really evil -- the case for war has come increasingly to rest on credibility. You see, say the hawks, we've already put our soldiers in position, so we must attack or the world won't take us seriously.

But credibility isn't just about punishing people who cross you. It's also about honoring promises, and telling the truth. And those are areas where the Bush administration has problems.

Consider the astonishing fact that Vicente Fox, president of Mexico, appears unwilling to cast his U.N. Security Council vote in America's favor. Given Mexico's close economic ties to the United States, and Mr. Fox's onetime personal relationship with Mr. Bush, Mexico should have been more or less automatically in America's column. But the Mexican president feels betrayed. He took the politically risky step of aligning himself closely with Mr. Bush ? a boost to Republican efforts to woo Hispanic voters -- in return for promised reforms that would legalize the status of undocumented immigrants. The administration never acted on those reforms, and Mr. Fox is in no mood to do Mr. Bush any more favors.