Hi there,

It is impossible to summarize such a complex subject in one simple comment in my view. What I can do for you is mention that while many states still officially deny Israel's right to exist, that is not what the main issue has been since roughly 1993. Jerusalem has been Israel's capital since 1948, but it has been the capital of Jewish thought for thousands of years, and was the capital of the Jewish kingdoms thousands of years ago. The dispute arises in how Israel came to be. In 1947, the UN proposed, through a commission's report that was amended by the UN General Assembly slightly, to create a Jewish and Arab state side-by-side in the area today known as Israel and the West Bank and Gaza. This proposal passed, but it was a nonbinding recommendation to the General Assembly, and was not implemented because while Jewish leaders accepted it (some fringe groups did not), the Arab population and the surrounding Arab states did not. The plan included a corpus separatum agreement for Jerusalem, which would have placed Jerusalem under international control. This was the catalyst for a civil war, which turned into an international war when the Arab states invaded the newly declared state of Israel on May 15, 1948, the day it declared independence. During this war, Jerusalem was split; Jewish forces managed to fight their way to recapture Western Jerusalem, while Jews were expelled from East Jerusalem and the Jordanians took control of it (as well as the Temple Mount/Haram al-Sharif, the holiest site for Jews and third-holiest for Muslims). Jordan annexed the West Bank and East Jerusalem, but eventually lost it to Israel when they attacked Israel (it was already at war with Egypt and Syria) in 1967. The previously split nature of the city, coupled with the general position that the international community that it should be internationalized, has made it contentious. Even so, for decades countries have traveled to Jerusalem to meet with Israel's government, which is headquartered there, and ambassadors present their credentials to Israel's President (who has a largely ceremonial title) and to meet with the Israeli Prime Minister (real head of government) in Jerusalem, which Israel has unified under one city title. The controversy is that, though Jordan and not the Palestinians controlled East Jerusalem from 1948-67, and that it was split by a war started by the Arab states in 1948, Palestinians now claim East Jerusalem, and much of the world has maintained that they should receive at least part of it in any peace deal, on the basis of popular sovereignty and self-determination (the eastern half is mostly Arab, and the world does not recognize the Jewish communities established there after 1967 as legal, which is another discussion in and of itself). The fear, then, has historically been that recognizing Jerusalem as Israel's capital would make it impossible for Palestinians to have it as their capital as well, and thus there has been fear that this would make the Arab world angry, resulting in diplomatic crises and riots and possibly even wars. The current situation is another story entirely, but one could say that following the Gulf War in 1991 and the actions of 9/11, skirting the 20 year rule, as well as more recent crises, this fear has been challenged.