The four key issues were: 1) the nature and borders of a Palestinian state; 2) the status of Jerusalem; 3) Palestinian refugees; and 4) Israeli settlements in the occupied territories. They were the most difficult, individually and collectively, because they represent the fundamental issues of Israeli control and Palestinian national aspirations. Further, although they are all subject to international law and specific UN resolutions, Israel (backed by the U.S.) rejects international jurisdiction and even relevance.