The Arab League was formed in Cairo on 22 March 1945 with six members: Egypt, Iraq, Transjordan (renamed Jordan after independence in 1946), Lebanon, Saudi Arabia, and Syria. Yemen joined on 5 May 1945. Since its formation the Arab League has promoted the Palestinian Arab cause in the Israeli–Palestinian conflict, including by imposing the Arab League boycott of Israel. The Arab League opposed the United Nations Partition Plan for Palestine in 1947. On 15 May 1948, the then seven Arab League members coordinated an invasion of what was by then the former British Mandate, marking the start of the 1948 Arab–Israeli War.