Page "History of Israel" Paragraph 67

The British Mandate ( in effect, British rule ) of Palestine, including the Balfour Declaration, was confirmed by the League of Nations in 1922 and came into effect in 1923.

The boundaries of Palestine were drawn by the British and first included modern Jordan, which was removed from the territory by Churchill a few years later.

Britain signed an additional treaty with the United States ( which did not join the League of Nations ) in which the United States endorsed the terms of the Mandate.