The Judas Gate — Jack Higgins

A disturbing tape has made its way to British intelligence, and from them to the new President of the United States: battlefield chatter from an ambush in Afghanistan, in which twelve U.S. Army Rangers and a British medical team died. Most of the Taliban voices are Afghan, but not all of them-the voice of the commander bears an Irish accent. The idea that one of their own could be responsible for such a massacre is appalling, and Sean Dillon is put in charge of hunting down the traitor. But Dillon has his own way of doing things and, he will eventually discover, so does his quarry. Dillon will not only be going to war-the war will be coming to him.