One of the strangely durable right wing talking points is that what differentiates G.W. Bush's presidency from Obama is that there were no terrorist attacks on Bush's watch. Seriously.
The operating assumption seems to be that September 11 doesn't really count, maybe because we weren't on notice (despite the Aug. 6, 2001 presidential daily briefing memo warning that bin Laden was "determined" to attack the US, perhaps by hijacking planes) and hadn't geared up our new hypertrophied security apparatus. So Bush gets a pass on the largest terrorist attack on U.S. soil because of what he did afterwards. Obama on the other hand, gets tagged with the failed Times Square bombing, the attempted Christmas Day bombing, and the Fort Hood shootings. Without diminishing the potential dangers of the failed attacks and the losses incurred at Fort Hood, it seems odd that the repeated refrain is that the attack and attempted attacks during Obama's presidency prove that somehow he is weaker on security issues than was Bush.
The right's repeated claim that there were no terrorist attacks on Bush's watch is another example of what Brian Massumi has called an "affective" truth, and what Stephen Cobert has described as "truthiness": it's not a factual truth, but an emotional one. If you believe Republicans are stronger on national security, then it follows that we were more secure under Bush than under Obama and there must not have been significant terrorist attacks during the Bush era. The odd thing, of course, is that the whole discussion stems from the 9/11 attacks, which made the issue of "who's stronger on terror" a political talking point in the first place. The attempt to dissociate Bush from 9/11 -- the defining event of his political legacy -- is a vexed but ongoing one.
Rudy Giuliani famously had to back off his assertion that, "We had no domestic attacks under Bush. We’ve had one under Obama." More recently right wing talk jock Mike Gallagher is repeating the refrain, noting in a recent interview on Fox News, that, "With George Bush, there were no acts of terror under his watch." The double logic at work is to make the whole discussion about 9/11 while at the same time acting as if it is so big that it's outside the discussion. It is portrayed as the defining exception, rather than as one more in an ongoing series of terror attacks. It's a difficult logic to parse.
I suspect the whole misguided rhetoric about how everything "changed" after 9/11 contributes to this oddly durable "not-on-his-watch" meme. If everything changed, than what happened before belongs to a different era -- an era when, apparently, you couldn't be blamed for ignoring one more threat from an obscure extremist -- after all, nothing like it had ever happened before.