From Cheney's speech:
This didn't get much coverage:
"You cannot keep just some nuclear-armed terrorists out of the United States, you must keep every nuclear-armed terrorist out of the United States."
What's the situation these days with nuclear-armed terrorists? How many nuclear-armed terrorists are out there? How many nukes do they have? What kind of nukes? Why haven't they detonated at least one bomb somewhere in the world, to show they mean business, in the last ten years? Etc.
Yeah, if there are any nuclear-armed terrorists, I'd be far more worried to be an Israeli than an American...
Public nuclear tests are what nation states do, the assumption being that a public test shows that they have not just obtained a weapon, but have established a manufacturing pipeline and are producing more weapons.
If AQ were to "test" a nuclear weapon, then the world would be forced to neutralize the threat. Right now, AQ and the Taliban are trying to thread the difficult needle of taking over Pakistan without arousing the world to stop it from happening. The last thing they need is to galvanize the world against them.
After they have secured Pakistan's arsenal of nuclear weapons, we may see things change.