The Second Saladin - Stephen Hunter

A second chance...
In the windswept sands of the Middle East, Paul Chardy fought side by side with Ulu Beg: one, a charismatic, high-strung CIA covert warrior, the other a ferocious freedom fighter. Then Chardy fell into the hands of the enemy, and Beg was betrayed. Now the two men are about to meet again.
A second gun...
Beg has come over the Mexican border under a hail of bullets—determined to assassinate a leading American political figure and avenge his people's betrayal. The CIA wants Chardy to stop the hit. Chardy wants to save Beg's life.
Between the two men is a tragic past, a failed mission, and a woman who knew them in war—and who knows their secrets now. Around both men is a conspiracy of lies and violence that reaches back to the Cold War. But as Beg moves in for his kill and as Chardy breaks loose from his handlers, a terrible truth begins to emerge: somewhere, someone wants both men to die.