Here's what looks like a causal argument–or a causal inference at least–wrapped up in another causal  explanatory inference.  The second one is an ad hominem, the first likely a causal fallacy.  Robert Kagan, of hawkish foreign policy fame writes.

Judged on its own terms, the war on terror has been by far Bush's greatest success. [1] No serious observer imagined after September 11 that seven years would go by without a single additional terrorist attack on U.S. soil. [2] Only naked partisanship and a justifiable fear of tempting fate have prevented the Bush administration from getting or taking credit for what most would have regarded seven years ago as a near miracle. Much of the Bush administration's success, moreover, has been due to extensive international cooperation, especially with the European powers in the areas of intelligence sharing, law enforcement, and homeland security. Whatever else the Bush administration has failed to do, it has not failed to protect Americans from another attack on the homeland. The next administration will be fortunate to be able to say the same — and will be contrasted quite unfavorably with the Bush administration if it cannot."[numbers inserted]

While there thankfully hasn't been another attack (aside from the Anthrax attacks) on U.S. soil, there have been numerous terrorist attacks on U.S. allies (Britain, Spain, Bali, etc.) and U.S. interests (Pakistan, Afghanistan, Iraq, Jordan, and so on).  Aside from the unsettling progress in Afghanistan and Iraq, one might suggest (as many terrorism experts have) that no terrorist attack was planned or attempted on U.S.soil.  So Kagan might be claiming credit for nothing.  In light of such observations, Kagan can hardly claim that "naked partisanship" (and fear of jinxing it) have prevented the Bush administration from taking credit.

So the second claim assumes only the weakest objections to credit-mongering (which, by the way, the Bush administration has not been shy of pointing out), when a person of Kagan's calibre ought to know better.  Given the existence of such views, Kagan ought to be far more circumspect when it comes to definitive causal assertions of the sort that the Bush Administration is responsible for stopping or otherwise preventing attacks on US soil–their mere absence is not evidence for its success.  Besides, given its unique ability to thwart terrorism here, our Allies might wonder why we can't be more helpful to them in this regard.

In fairness to Kagan, there's much more to the argument than cited here.  But then again, a silly argument is a silly argument.