It's been 10-15 years, and I don't have a copy handy, so perhaps I've got some of the details wrong. I'll take your word for it, but it seems to me that I remember that the reason Mr. Clark and his team targets the Mullah for assassination in either that or a later novel is because the Mullah gave extensive material support to those who did the Nuke strike in Colorado. Could be wrong, if I am apologies to Mr. Clancy. But my point was that it seemed, as a plot device in a novel, a pretty weak "swap" in combat terms: one deranged Mullah for one American city, with the Americans getting the worst end of the deal.
Then again, to be fair, I keep reading his novels as they come out (along with most of his non-fiction offerings, which I really enjoy), so I must not dislike them *too* much or I'd quit reading. Not a big deal, just my .02 cents.
In fact, I stopped reading Clancy after "The Dragon and The Bear", because I found the plot was too weak, and because subplots were announced and never pursued.
AFAIK, in the SUm of all Fears, the bad guys are terrorists, a combination of PLO/Baader Gang, who want to crash down the new world order. They detonate a nuclear warhead in a US stadium and orchestrate incidents in Germany to make the USA and Russia attack each other. As a a second cover story, they plan on accusing Iran of being the masterming behind the attack, to entice a US strike against it and ruin every prospect of peace in the Middle-East - and that's why Ryan oppose it.
The pinpoint attack on a Mullah is in another novel - I guess it's Executive Orders, where Iran really is the villain this time.
Your talking about "executive orders". Clark and Chavez use a guide in a smart bomb on the head mullah of Iran. But this is after the portions of the US Army has crushed the combined army of Iraq and Iran.