When you have read all of TOM CLANCY, try one of these:

Richard Aellen Crux
Larry Bond Vortex
Dale Brown Flight of the Old Dog
Stephen Coonts Flight of the Intruder
Harold Coyle Team Yankee
Clive Cussler Raise the Titanic
Greg Dinallo Rockets Red Glare
Sean Flannery Winner Takes All
David Hagberg Desert Fire
Payne Harison Storming Intrepid, Thunder of Erebus
Stephen Hunter Point of Impact
Dean Ing Butcher Bird
Philip Kerr The Grid
Poyer, David The Gulf, Tomahawk
Patrick Robinson Kilo Class, Nimitz Class
Joe Webber Defcon One