I read this when it first came out, back when I was in my thriller phase. It's my favorite Clancy book - probably because there's more to the characters than in his previous submarine books.

Jack Ryan is a CIA analyst and ex-Marine who unintentionally gets caught in the fight for Northern Ireland. His actions foil an attempt by a factional group to kidnap a member of the royal family, and makes him a target of terrorists. Jack's family becomes the one in danger as the war crosses the Atlantic and ends up in his backyard--literally.

Written in a time when the IRA was the most feared terrorist organization around, the book is dated. But that doesn't take away from the suspense. Of course, there is the movie version too, which does do a pretty good job of capturing the book.