their leaders imprisoned and fined. A total of 7,000 Jews were expelled, many with merely a satchel. Antisemitism in Communist countries Following the war, a series of antisemitic purges began in Communist countries. Some 11,200 Jews from Poland immigrated to Israel during the 1968 Polish political crisis and the following year. War of Attrition Following the war, Egypt initiated clashes along the Suez Canal in what became known as the War of Attrition. Palestinian terrorism As a result of Israel's defeat of Arab armies, the Palestinian leadership concluded that the Arab world was not able to militarily defeat Israel in open warfare, which in turn led to an increase in terrorist attacks with an international reach. While the Palestine Liberation Organization (PLO) was established in 1964, it became militarily active after the Six-Day War; its actions gave credibility to those who claimed that only terror could end Israel's existence. Also after the war, the Popular Front for the Liberation of Palestine emerged, with its leader George Habash speaking of turning the occupied territories into an "inferno whose fires consume the usurpers". These events led to a series of hijackings, bombings, and kidnappings that culminated in the massacre of Israeli athletes during the 1972 Munich Olympics. Peace and diplomacy Following the war, Israel made an offer for peace that included the return of most of the recently captured territories. According to Chaim Herzog: The 19 June Israeli cabinet decision did not include the Gaza Strip and left open the possibility of Israel permanently acquiring parts of the West Bank. On 25–27 June, Israel incorporated East Jerusalem together with areas of the West Bank to the north and south into Jerusalem's new municipal boundaries. The Israeli decision was to be conveyed to the Arab nations by the United States. The U.S. was informed of the decision, but not that it was to transmit it. There is no evidence of receipt from Egypt or Syria, and some historians claim that they may never have received the offer. In September, the Khartoum Arab Summit resolved that there would be "no peace, no recognition and no negotiation with Israel". However, as Avraham Sela notes, the Khartoum conference effectively marked a shift in the perception of the conflict by the Arab states away from one centred on the question of Israel's legitimacy, toward one focusing on territories and boundaries. This was shown on 22 November when