It is a cynical but time-honoured practice in Middle Eastern politics: the statesmen who decry the political and humanitarian crisis of the approximately 3.9 million Palestinians in the Israeli-occupied West Bank and in Gaza ignore the plight of an estimated 4.6 million Palestinians who live in Arab countries. For decades, Arab governments have justified their decision to maintain millions of stateless Palestinians as refugees in squalid camps as a means of applying pressure to Israel. The refugee problem will be solved, they say, when Israel agrees to let the Palestinians have their own state. Yet in the two decades since...