Final answer:
Jerusalem was placed under UN supervision because it was considered a holy city by both Jews and Arabs. This international trusteeship was intended to maintain access and protection for all faiths, as stipulated by UN Resolution 181 in 1947.
Step-by-step explanation:
The reason why Jerusalem was placed under UN supervision following the creation of Israel was because both Jews and Arabs considered it to be a holy city. Jerusalem has significant religious importance to Jews, Christians, and Muslims, therefore, under the United Nations' plan, the city was to be governed as an international trusteeship to ensure its protection and accessibility to all faiths.
The United Nations recognized the complexity of designating sovereignty over a city sacred to both emergent Israeli and Arab Palestinian national movements. To navigate this delicate situation, the UN proposed that Jerusalem should become an international city under UN administration, which was stipulated in the UN Resolution 181 of 1947, part of the partition plan for Palestine. However, by 1948, during the first Arab-Israeli war, the city was divided, with West Jerusalem controlled by Israel and East Jerusalem by Jordan.
In 1980, Israel's Jerusalem Law declared the city as its 'eternal capital,' but this claim was not widely recognized internationally, resulting in most foreign embassies remaining in Tel Aviv. The contentious nature of the city's status remains a critical factor in the Israeli-Palestinian conflict, underscoring the importance of the initial plan to place Jerusalem under UN supervision.