Sovereignty over the Temple Mount is apparently so explosive to the Arab world that the question may have torpedoed the Camp David summit in July and helped spark the Palestinian violence of the past three months.
Now it's becoming clear just how explosive it is for Jews as well.
Amid new indications that the Israeli government is ready to cede sovereignty over the holy site in exchange for Palestinian renunciation of the "right of return" for refugees, American Jews are going on the offensive.
Israel knows best when it comes to borders and security arrangements, say some American Jewish activists, but Jerusalem -- and the Temple Mount -- is a different story.
"Israel Must Not Surrender Judaism's Holiest Site" reads a new advertisement initiated by the Zionist Organization of America (ZOA) and signed by some 30 prominent American Jews.
The ad portends a potential confrontation between the Israeli government and important segments of American Jewry at a time when Israeli Prime Minister Ehud Barak may need international as well as internal Israeli backing for any peace deal with the Palestinians.
The signatories to the ad include hard-liners and moderates, including six past chairpeople of the Conference of Presidents of Major American Jewish Organizations.
The ad is aimed at influencing both American Jewish and Israeli audiences and will run in U.S. Jewish and Israeli media this week, said Morton Klein, president of the ZOA.
"The Muslims wouldn't dream of giving away part of Mecca or Medina; the Christians wouldn't dream of giving away part of the Vatican," Klein said.
"And no Israeli leader has the right to give away the essence of the Jewish people that is embedded in the Temple Mount."
New U.S. proposals presented to Israel and the Palestinians over the weekend call for Israel to give up sovereignty over the Temple Mount and for the Palestinians to give up the right of refugees displaced during Israel's creation to return to the state.
The Clinton administration is seeking a quick response from both sides to determine if a peace deal can be sealed before he leaves office on Jan. 20.
The Temple Mount's upper level houses the third holiest shrine in Islam while sitting atop the remains of the First and Second Temples, the holiest site in Judaism.
Some rabbis in Israel forbid Jews from treading on the Mount, for fear of defiling its sacred ground. Israeli officials, including Barak, have in recent statements indicated willingness to recognize the Palestinians' de facto control over the upper level of the Temple Mount while steering clear of the term "sovereignty."
At the same time, Israeli officials stress an agreement would ensure Jewish links to the site and access to the subterranean levels where the remains of the Temple are believed to be located.
"We will do nothing to impair the affinity of the Jewish people to the site," said Barak, who has also come under intense pressure from Israeli political and religious leaders against yielding control of the site.
U.S. Jews opposed to concessions on the Temple Mount are citing those leaders in making their case.
The National Council of Young Israel this week cited Israel's Chief Ashkenazi Rabbi Yisrael Meir Lau, who was quoted in the Israeli daily Ha'aretz saying that to abandon the Temple Mount "means abandoning the tradition of thousands of years."
"The situation, de facto, is unfortunately that the Palestinians and the Muslims control the Mount, but to grant this reality a de jure authorization would violate the public's trust," Lau was quoted saying.
U.S. Jews also cite Israeli hard-liners Natan Sharansky and Ariel Sharon, who is challenging Barak in the upcoming Israeli elections.
The pair contend that Diaspora Jews must have a say over the fate of Jerusalem and the Temple Mount. In the Arab world, too, leaders warned Palestinian Authority President Yasser Arafat that Jerusalem is a matter for the entire Muslim world.
On the other side of the spectrum, meanwhile, American Jews in the peace camp are reiterating that they trust the Israeli leadership and electorate to decide for themselves what is in Israel's best interests. When the Conference of Presidents recently issued a clarion call to American Jews to visit Israel to boost its sagging tourism industry, it rankled several in the peace camp by including the mantra of Jerusalem as "the eternal and undivided capital."
Avram Lyon, executive director of the Jewish Labor Committee, sent a letter to Ronald Lauder, chairman of the Conference of Presidents, to complain.
"It's clear that Jerusalem or parts of Jerusalem are in fact in play and being discussed," Lyon said. "It would be rash and careless to imply that the Jewish community of the United States stands in opposition to the government of Israel."
Malcolm Hoenlein, executive vice chairman of the Conference, denied there was any political intent to the statement, and said "it does not preclude Israel from doing anything" during the negotiations. As for the ZOA-initated ad, it was launched in response to comments Israeli Absorption Minister Yuli Tamir reportedly made last week in New York.
Tamir was quoted as saying that Israel "must make painful concessions, renouncing one way or another our sovereignty over the Temple Mount if necessary."
But, she added, "on the ground, things wouldn't really change."
A few days later, Israeli Foreign Minister Shlomo Ben-Ami reportedly made similar comments in a conference call with American Jewish leaders.
Signatories of the ad said they hoped to send a strong message to Barak.
"I don't think Israel has to have sole sovereignty of the Temple Mount, but I think it's a strategic error to say it's not important, not vital to the Jews," said Rabbi Jerome Epstein, executive vice president of United Synagogue of Conservative Judaism.
"I understand that I'm not a factor in this decision. I don't live in Israel and I don't have a vote. The prime minister can ignore me, but I can still use my voice and whatever influence my voice has."
The ad also quotes Hoenlein and a controversial statement he made three months ago.
At that time, Hoenlein said, "In future years, all of us will have to answer our children and grandchildren when they ask us why we did not do more to protect their heritage and safeguard Har HaBayit" -- the Temple Mount.
Hoenlein, who made his remarks before a Jewish group, was accused by some as attempting to derail Barak's effort to negotiate control of the Mount.
Hoenlein said in an interview last week that his comments "are just as valid today as they were then."
"Israel has a right to make decisions that affect its security. All Jews have a right to discuss it, but it's up to the government of Israel," he said.
The "Temple Mount is a different issue. It belongs to all Jews, it is the inheritance of all Jews, and all Jews have a vested interest in it."
Morton Klein of the ZOA threatened that if Barak dealt away sovereignty over the Mount, he and others would launch a campaign to undermine its implementation.
"I can tell you that almost every major Jewish leader I've spoken with will do virtually everything in their power to ensure that any attempt to give away the spiritual soul of the Jewish people does not succeed," he said.
But some think that in the end, American Jewry will defer to the Israeli people -- and its government. "There has been a bedrock principle that the American Jewish community gives great deference to the Israeli government's decisions on matters of war and peace," said Martin Raffel, associate executive vice chairman of the Jewish Council for Public Affairs. "I expect that will continue, including on issues affecting the Temple Mount."
Epstein and others concede that if Israelis approve by referendum a deal on the Mount, they, too, would ultimately accept it.
"If the prime minister comes back with something the Israelis are willing to buy, then I would also buy it. I would -- reluctantly, unhappily," Epstein said.