In 1917, the British government issued a public statement known as the Balfour Declaration during World War I announcing support for the establishment of a "national home for the Jewish people" in Palestine, then an Ottoman region with a small minority Jewish population.
This was the declaration:
"His Majesty's government view with favour the establishment in Palestine of a national home for the Jewish people, and will use their best endeavours to facilitate the achievement of this object, it being clearly understood that nothing shall be done which may prejudice the civil and religious rights of existing non-Jewish communities in Palestine, or the rights and political status enjoyed by Jews in any other country."