The transcript of Obama's remarks from a recent fundraiser contains a mystifying Freudian slip [Mystery solved by AliceH in comments; see HMMMM... below] on the subject of ISIS and our national security (my emphasis):
We have, since 9/11, built up the capacity to defend ourselves from terrorist attacks. It doesn’t mean the threat isn’t there and we can’t be -- we don’t have to be vigilant, but it means that we are much less vulnerable than we were 10 or 12 or 15 years ago.
As someone almost said, eternal vigilance is the price we don't have to pay. Well, Obama needn't worry - I doubt anyone considers him to be excessively vigilant.
But the mystery is, what word was the Greatest Speaker In The History Of Forever looking for? He clearly was fumbling for something, but what? "We can't be complacent"? "We don't have to be paranoid"? Or did "don't" creep in to the sentence about vigilance just as Freud would have predicted?
Well, I would not presume to put words in Obama's mouth. "We don't have to be vigilant" it is, unless someone at the White House wants to clarify that.
Presumably he misspoke, and understandably - Obama must be exhausted after working a whole week. He probably needs a vacation.
HMMM... What Obama said makes more obvious sense if the stray "we can't be" is dropped. "It doesn't mean" relates to both "the threat isn't there" and "we don't have to be vigilant":
It doesn’t mean the threat isn’t there and  we don’t have to be vigilant, but it means that we are much less vulnerable...
OK, maybe I need a vacation.