Original sentence: Israel's position on refugees was that the Arab states were responsible for the Palestinian refugee problem since it was their aggression that caused the initial tragedy, and that therefore it was an Arab problem
Edited sentence: Israel's position on refugees was that the Arab states were responsible for the Palestinian refugee problem since it was their aggression that caused the initial tragedy, and that therefore it was an Arab problem, even though more than half of the Palestinian refugees were forced to leave from December 1947 (following the approval of United Nations Partition Plan for Palestine( to May 15, 1948, (the time of Arab declaration of war on Israel) climaxing with the Deir Yassin massacre