Balance of Power - Tom Clancy

Spain is a nation poised to suffer its worst internal strife in centuries. Certain well-placed Spanish diplomats sense it. Op-Center intelligence corroborates it. All the United States and Spain have to do is find a way to avert it. Before they can, an Op-Center representative is assassinated in Madrid on her way to a top secret meeting. Now all fears are confirmed. Someone very powerful wants another Spanish civil war–no matter what the cost.