President Sadat believed that Egypt's economic, political, social and military problems were a result of the Six-Day War. He believed the solution to these problems lay with erasing the humiliation of the 1967 defeat, which required regaining the Sinai. In 1971 Sadat began the coordinated political and military groundwork to achieve this. In February, he proposed a phased Israel withdrawal from the Sinai, which would involve a reopening of the Suez Canal, and Israeli fulfillment of the UNSCR 242, including resolving the Palestinian refugee problem. In return Egypt would sign a peace treaty with Israel and reestablish relations with the United States. However Israeli insistence on retention of territory necessary for its security ended diplomatic efforts.