There was a guy in our dorm (1980's post-barracks bombing) from Lebanon who described it as the following: The arabs fight each other with huge blood feuds dating back centuries. Then Israel arrives, and all (or most) of the feuds stop and they all band together to fight the Israelis. If the Israelis were gone or somehow out of the picture, the arabs would go back to fighting each other to the death. Basically, "we hate each other, but we'll work together to fight our common enemy ... once he's gone we'll go back to fighting each other".