"President George W. Bush said on Wednesday terrorists had converged on Iraq and that pulling U.S. troops out would only embolden them." - Reuters
They have converged on Iraq because George W. Bush opened the borders of Iraq.
Bush's invasion of Iraq emboldened the terrorists, gave them a training ground in Iraq and allowed them to spread into a country that had previously been denied to them.
The result is that he has created a situation where there are NO good options, and he is trying to use the fact that he has painted us into a corner as the new justification for continued war.
Reasonable people may differ on the solution, and some - probably most - may think that it is necessary to stay in Iraq, since Al Qaeda is certainly there NOW, although they weren't there before Bush's Bungle.
But why the hell would you leave the guy in charge who CREATED the disaster in the first place?