John McCain and Lindsey Graham unwittingly undermine their own argument:

What’s worse, the administration’s failure on Syria is part of a broader collapse of U.S. credibility in the Middle East. As recent reports make clear, Israel and our Gulf Arab partners are losing all confidence in the competence, capability and wisdom of the administration’s diplomacy in the region.

As far as I can tell, Saudi and Israeli concerns about U.S. diplomacy in the region are not that it will fail, but that it could be successful in reaching an agreement with Iran that they don’t like. They may be questioning the wisdom of U.S. diplomacy, but that is only because it is not indulging their preferences. Saudi Arabia and Israel are free to disapprove of U.S. diplomatic efforts, but if a diplomatic solution to the nuclear issue is possible I’m not sure why Americans should care very much what these other governments say about it. The U.S. and its clients are bound to have divergent interests from time to time, and they will naturally disagree about specific decisions, but the U.S. shouldn’t allow the griping of a few clients to push it into taking a harder line with Iran than it considers necessary just as it shouldn’t feel compelled to intervene more directly in Syria’s conflict simply because some clients would prefer that.

McCain and Graham are griping here about lost U.S. “credibility,” but all that they’re really saying is that they’re unhappy that their more aggressive preferences for Syria and Iran policy have been ignored, which is the same complaint that the Saudi and Israeli governments have been making. It’s reasonably safe to say that any policy would satisfy the Saudis, Netanyahu, and American hard-liners would not be good for U.S. interests, so the fact that they are all displeased with current policies in the region may be one of the best arguments in their favor.

Paul Pillar makes a related observation about U.S. credibility in the region:

Displeasing other states, when there has been no failure to live up to a treaty commitment and when the other states—as is true of both Israel and Saudi Arabia—have major differences of interest with the United States as well as some shared interests, has nothing to do with a failure of credibility. Consistent pursuit of the United States’s own interests is much more of a foundation for maintaining credibility.