I can add two more: ideology or a moral crisis.
Ritter, AFAIK, is a tremendous UN supporter. It may be that he sees that if this comes to a confrontation the UN will be shown to be useless. He is desperately trying to avoid this.
During his trips to Iraq, he sees the tremendous suffering occasioned by sanctions. Since Hussein will not relent and US politicians need the fig leaf of sanctions to prove they are "tough" (but will not go through a regime change), there is no way out of this mess. Eventually, Ritter(v.2002) figures Ritter(v.1998) is obviously part of the cause of the problem, since he(v.1998) refused to lie about Hussein's lack of cooperation. So Ritter(v.2002) reverses course.