Oh, for crying out loud. The parent is NOT, I repeat NOT, flamebait.
Well, ok. Calling Carter a dolt was uncalled for, but so is saying the same of Bush. You see, the government has a bit of an unwritten rule around the pronunciation of "nuclear". It's a rule that was introduced for propaganda purposes, but hasn't always worked like they want it to.
Basically, government officials always pronounce the weapons as "nucular arsenal". This pronounciation is intended to associate the term with "bad", "danger", and "massive destruction". When they're referring to nuclear in the context of power generation or some other "good" aspect, it's supposed to be properly pronounced as "nuclear".
Of course, it didn't exactly work out as planned. The public sees no difference between "nucular" and "nuclear". Worse yet, the politicians often get the two mixed up anyway, thus failing at the message they're supposed to be delivering. But the concept is still out there and the Presidents have tried to somewhat follow it.
If you're interested in the origin of the use of "nucular" in the government, it goes back to Eisenhower. Eisenhower pushed a program known as "Atoms for Peace". Unfortunately, he couldn't pronounce "nuclear" correctly to save his life. As such, the term "nucular" ended up in the government lexicon.
Besides, there's a long tradition of never contradicting the President. Past or present. A tradition abused by the airforce to get the name of the RS-71 changed to SR-71. But that's another story... ;-)