New White House standard on WMD evidence

From Tim Russert's interview with UN ambassador John Bolton on today's "Meet the Press":

RUSSERT: Has North Korea's nuclear capability increased during the Bush presidency?

BOLTON: I think we have no way of being certain of that one way or the other.

So the White House now has to be "certain" to make statements about the development of weapons of mass destruction? We have far more evidence that North Korea's nuclear program has progressed dramatically under President Bush than, say, Defense Secretary Donald Rumsfeld had to support his claim that "We know where [the weapons of mass destruction] are. They're in the area around Tikrit and Baghdad and east, west, south and north somewhat." And when will this standard will be applied to statements about Iran's nuclear program? On the other hand, Bolton's statement does sound a lot like the administration's rhetoric about global warming...