With all due respect to Tom Clancy, who was my favorite thriller writer for years before he fell prey to the boredom of success, I would like to introduce you all to the greatest writer of thrillers alive on Earth today: Britain's own Andy McNab.
McNab (a pseudonym) was a highly decorated, long-time soldier/operator in the Brits' Special Air Service. The SAS is one of the grand-daddies of Special Forces and is still, I gather, highly regarded in the special operations world.
McNab combines obvious real-life know-how, an ability to devise and hold together an interesting plot, a great ear for realistic dialog employing a lot of Brit slang, and the ability to clearly write outstanding action sequences. His books are full of tradecraft and techniques that are realistic as hell, his characters are real people with real motivations, and his action fairly leaps off the page.
Most of McNab's work is fiction, starring an ex-SAS operator named Nick Stone. Very little goes right for Nick, but he reacts to the situation as it unfolds and comes through, almost always worse, and sometimes a lot worse, for the wear. Nick narrates the action in the first person and, while we never get a clue what he looks like, he's a keen observer of the people and places around him. He is lethally skilled, but suffers from no direction in life and has, at times, battled out-and-out depression. With good reason - his life is crap. He's very good at a whole slew of things that most people can't even imagine, but has no real-world skills. Everyone he's ever cared about has been killed, usually very messily and right in front of him.
Nick's adventures start in Remote Control and carry on through eight books so far, the most current of which is called Aggressor. Some of the books are better than others. They do form a series; characters and situations carry from one to the next, so it probably helps to read them in order. The best of the lot are Remote Control, Firewall, and Dark Winter.
I encourage you to pick up Remote Control and enjoy Andy's fine work.