I loved all the Jack Ryan stories. Those were books that I just couldn't put down. I have to admit though, after 9-11 I couldn't help but connect the idea to Debt of Honor. That story, along with Executive Orders is my favorite combination of reads.
The Clark character... he is the total Bad Ass. His prequel story is also at the top.
"The life you lose may be your own" - Drunk dude at the bar