You wold think THIS would give them some legitimacy
https://history.state.gov/milestones/1945-1952/creation-israel#:~:text=On November 29%2C 1947 the,mandate was scheduled to end.
In May 1946, Truman announced his approval of a recommendation to admit 100,000 displaced persons into Palestine and in October publicly declared his support for the creation of a Jewish state. Throughout 1947, the United Nations Special Commission on Palestine examined the Palestinian question and recommended the partition of Palestine into a Jewish and an Arab state. On November 29, 1947 the United Nations adopted Resolution 181 (also known as the Partition Resolution) that would divide Great Britain’s former Palestinian mandate into Jewish and Arab states in May 1948 when the British mandate was scheduled to end. Under the resolution, the area of religious significance surrounding Jerusalem would remain a corpus separatum under international control administered by the United Nations.