The British mandate in Palestine was set to end in 1948, but the issue of what would happen to the land became contentious as early as 1945. United Nations Resolution 181, or the Partition Resolution, was set to divide that mandate into Jewish and Arab regions upon its expiration.
In 1945, President Franklin Roosevelt had told the Arabs that the United States would stay out of issues regarding Palestine unless they talked to both Jews and Arabs first. However, President Roosevelt passed away in 1945, and Harry S. Truman became president. He asked several experts to form a commission and review Palestine, and he eventually approved a recommendation to allow 100,000 displaced persons into Palestine and publicly supported a Jewish state. This became Resolution 181, which the United States supported even though the U.S. State Department disagreed.
The alternate suggested by the State Department was creating a United Nations trusteeship over Palestine limiting Jewish immigration and creating distinct Jewish and Arab provinces. As the expiration of the mandate approached, many Arab nations threatened to attack the territory. However, once the partition expired, the head of the Jewish Agency, David Ben-Gurion, established the State of Israel, and President Truman announced American recognition for this new country later that day.