So there was a big change in Ritter's outlook from 1998 to 2001.

Since he was in a position to observe the changes in Iraq, it probably accounts for the change in Ritter's position.

What was true in 1998, was no longer true in 2001.

We do not live in a stagnant world. Change happens all the time.
People who cannot change their minds according to changing circumstances are confined by dogma.

Someone should tell Bush this.