You said -- "Nonsense. The Soviets decided to put men onto the Moon. They failed. Details matter."
You forget their "objective". It was to be *first*. Once they failed in *that objective* -- they changed their decision. If they had a different objective -- like simply getting a man on the moon and not being first -- they would have succeeded. It was simply a "matter of time" and their decision. That's all.
Now, in regards to al-Qaida -- they don't have any "false decision" about "being first" -- and thus deciding to quit when they don't succeed. They have made the decision to fight the U.S., to defeat the U.S. (as it's part of their religion). It's not something that will change -- unless you eliminate the religion of Islam. That's why I advocate totally and thoroughly destroying the religion of Islam.
And so -- with them it's simply "make a decision and buy the details". They've got all the time in the world. They're patient and they can wait.
We can be successful in defending our borders and country from that kind of intrusion for 999 times. But, the *first time* we fail (even after 999 successes) -- "we lose". They've won.
And likewise, with them -- they can fail 999 times. And if they succeed *once* -- they've won exactly what they wanted.
There's you "math" for the equation....
Regards,
Star Traveler
"And likewise, with them -- they can fail 999 times. And if they succeed *once* -- they've won exactly what they wanted. There's you "math" for the equation...." 
It's poor math. If caught with even 1 nuke, Al Qaeda would face vast new challenges. Losing 999 would doom them; actually, they'd be doomed far earlier, and are probably already doomed due to our global successes in the war on terror.
Al Qaeda's idea of high tech is a box cutter on someone else's jumbo jet. Clean labs and nuclear construction/maintenance are vastly out of their hands.
Nor is North Korea going to risk 999 nukes to get one to a U.S. port. Nor will Iran. Iran is building long range missiles because they want a higher hit ratio than that; they already know that we are detecting and stopping anything even close to a nuclear component.
The 4 Libyan ships that we caught with centrifuges, for instance, were detected from the **traces** of radiation left from their prior legitimate enrichment usage.
Even washed, they weren't clean enough nor shielded by the ships' hulls enough to escape our detection.