American presidents have, with rare exception, spoken of Israel with biblical reverence.
If anything, the language has only gotten more pro-Israel with each successive White House administration since Harry Truman made the United States the first country to recognize Israel's independence in 1948.
Barack Obama has torn up the old script. If the policies of his administration toward Israel represent incremental change more than a break with the past, he talks about them in ways no previous president dared.
Mr. Obama's public endorsement of Israel's pre-1967 borders as the basis for a peace deal with the Palestinians has sparked outrage in Israel, on the U.S. right and from the powerful American Jewish lobby.
Just why Mr. Obama has chosen this tack, and why he has done so now, speaks both to the unprecedented change sweeping the Arab world and the 44th president's desire to ensure the United States does not squander a chance to reset U.S.-Arab relations by showing favouritism toward Israel.
It also reflects Mr. Obama's recognition that the elusive goal of Middle East peace has not been advanced by treating Israel with kid gloves. That has only put the United States on the outs with most of the Arab world.
But there are also big risks in Mr. Obama's approach. Domestically, it is largely at odds with American public opinion and the unshakeable solidarity toward Israel expressed by the Tea Party movement and Christian right. Both are likely to be major forces in the 2012 election.
And given Mr. Obama's already chilly relationship with Israeli Prime Minister Benjamin Netanyahu, the President's forthrightness may only lead to a hardening of positions on all sides.
"A peace based on illusions will crash eventually on the rocks of the Middle Eastern reality," Mr. Netanyahu said in the Oval Office Friday as Mr. Obama looked on uncomfortably. "While Israel is prepared to make generous compromises for peace, it cannot go back to the 1967 lines because these lines are indefensible."
On Thursday, Mr. Obama broke with the public pronouncements of his predecessors by explicitly calling for peace negotiations based on the borders of Israel that existed before the 1967 Six-Day War, the conflict that led to Israeli occupation of the West Bank and Gaza Strip.
Mr. Obama qualified his statement by referring to the "1967 lines with mutually agreed swaps." It was an implicit reference to Jewish settlements in the West Bank and East Jerusalem, territories that Israel might keep in exchange for ceding other land to the Palestinians. (Israel pulled out of Gaza in 2005.)
But the nuances were largely overshadowed by Mr. Obama's unprecedented language, as the President must have known they would be.
"The phrase in Obama's speech is not logically contradictory to earlier statements [by U.S. presidents]but it does push as far as possible toward the current position of much of the Palestinian leadership," George Washington University political science professor Nathan Brown explained. "The [George W.]Bush administration had pushed in the opposite direction, which explains in part the very angry official Israeli reaction."
In Ottawa, the Harper government refused to publicly endorse Mr. Obama's starting point for Middle East peace talks. A federal official, who spoke on the condition of anonymity, insisted that outsiders cannot dictate the basis for negotiations.
"If the two parties are of the view that this is a starting point, that is fine for them," the senior federal official said. "If it's border, if it's other issues, it has to be negotiated, it cannot be unilateral action."
In many ways, Mr. Obama's much-anticipated Middle East speech - broadcast live from the State Department on Thursday and directed as much at an Arab audience as an American one - underscored the similarities between his current foreign policy and that of Mr. Bush.
"The United States was founded on the belief that people should govern themselves," Mr. Obama said, in what many analysts considered an unsubtle echo of Mr. Bush's so-called ideals-driven Freedom Agenda. "And, now, we cannot hesitate to stand squarely on the side of those who are reaching for their rights."
The statement appeared to break with the pragmatic foreign policy that has been the trademark of the Obama administration until now. Yet, when it comes to the Arab-Israeli conflict, Mr. Obama is a die-hard realist, conscious of the panoply of U.S. interests at play in an oil-rich region facing a demographic, and potentially democratic, explosion.
Other presidents, particularly Dwight Eisenhower and George H.W. Bush, might have voiced the same concerns in private. But none really showed it in public. Indeed, until Mr. Obama took office, every U.S. president had expressed an emotional and spiritual bond with Israel.
"Our forces saved the remnants of the Jewish people of Europe for a new life and a new hope in the reborn land of Israel," Mr. Eisenhower said.
Lyndon Johnson spoke of how "the Bible stories are woven into my childhood memories as the gallant struggle of modern Jews to be free of persecution is also woven into our souls."
Jimmy Carter wrote that he considered a "homeland for the Jews to be compatible with the teaching of the Bible, hence ordained by God."
Bill Clinton may have the most uncritical U.S. leader of them all, often referring to his first journey to Israel as a "religious pilgrim."
Mr. Obama, who has yet to make his first visit to Israel since taking office, is at odds with a resurgence of pro-Israeli sentiment on the American right.
The defence of Israel is nothing short of a religious obligation among evangelical Christians. Tea Partiers belief in "American exceptionalism" and skepticism of the Arab world has made them staunchly pro-Israel.
Both groups' "rising political influence in the United States will lead to stronger support in Washington for the Jewish state," scholar Walter Russell Mead wrote recently in the journal Foreign Affairs. "This support does not proceed simply from evangelical Christian influence …[Tea Partiers]admire Israeli courage and self-reliance - and they do not believe that Arab governments are trustworthy or reliable allies."
It is little wonder that most of the Republicans seeking to challenge Mr. Obama for the presidency in 2012 immediately cast his speech as a "betrayal" of Israel.
Former Massachusetts governor Mitt Romney accused Mr. Obama of "throwing Israel under the bus," while ex-Minnesota governor Tim Pawlenty insisted that "at this time of upheaval in the Middle East, it has never been more important for America to stand strong for Israel and a united Jerusalem."
Still, while Mr. Obama used new language to describe the U.S. position toward Israel, his policies build on those of previous administrations.
"Clearly, the President used the term "1967 lines." But it's an evolution. It's moving one step further," said Fred Lazin, a visiting professor at American University's Center for Israel Studies in Washington.
Following negotiations in 2000 between Mr. Clinton, then-Israeli prime minister Ehud Barak and Palestinian Liberation Organization leader Yasser Arafat, the so-called Clinton Plan envisioned a Palestinian state that took in all but a tiny portion of the West Bank and Gaza.
In a 2004 exchange of letters, Mr. Bush assured Israeli prime minister Ariel Sharon that U.S. policy would not confine Israel to a strict adherence to its 1967 boundaries, also known as the 1949 "armistice lines."
"In light of new realities on the ground including already existing major Israeli [settlements in the West Bank] it is unrealistic to expect that the outcome of final status negotiations will be a full and complete return to the armistice lines of 1949, and all previous efforts to negotiate a two-state solution have reached the same conclusion," Mr. Bush said.
He added: "It is realistic to expect that any final status agreement will only be achieved on the basis of mutually agreed changes that reflect these realities."
Mr. Bush's reference to "mutually agreed changes" amounts to much the same as Mr. Obama's' "mutually agreed swaps."
What has largely changed is the position of the Israeli governments.
When Mr. Clinton came to office, Yitzhak Rabin was prime minister of Israel, and the Oslo Accords between Israel and the PLO were signed on the White House lawn.
In Mr. Rabin and, later, in Mr. Barak, the U.S. president found Israeli administrations willing to agree to relinquish the West Bank and Gaza Strip in exchange for security and other provisions from the Palestinian Authority.
Even the outbreak of the violent second intifada in 2000 did not diminish the coalition government's resolve to make a deal.
But that violent uprising changed public opinion. Mr. Sharon, followed by Ehud Olmert, and finally Mr. Netanyahu, all came to power at the head of coalition governments increasingly dependent on small ultra-nationalist parties. The latter consider the land of the West Bank sacred and are not willing to relinquish much, if any, of it.
Still, the majority of Israelis say they still are willing to give up the West Bank in exchange for peace. And Tzipi Livni, whose Kadima party received more votes and seats than Mr. Netanyahu's Likud party, was highly critical of his response to Mr. Obama's speech.
"Netanyahu is making Israel pay too a high price to save his coalition and ensure his personal survival," Ms. Livni was quoted as saying. "The prime minister has violated relations between Israel and the United States. He has endangered the security of Israel and its power of deterrence."
Indeed, some Israeli analysts believe the Obama speech offered Israel far more than it took away. The President blasted the Palestinian Authority's campaign to win state recognition at the United Nations this fall, as well as the "unity agreement" between the Fatah-led authority and Hamas, an organization still opposed to Israel's existence.
Even the matter of the 1967 boundary includes a provision that both Israel and the Palestinians must agree to any land swaps, giving Israel a veto over what it will give up.
"These points came straight out of the policy pages of the Prime Minister's Bureau in Jerusalem," said Aluf Benn, editor at large of the Haartez newspaper. "Netanyahu could not have asked for more."
Still, Mr. Obama took a calculated risk by becoming the first U.S. president to use the "1967 lines" formulation in a public speech. He did so despite a last-minute warning by Mr. Netanyahu, reportedly made to Secretary of State Hillary Clinton, to stay away from any such reference.
But Mr. Obama has made repairing America's image in the Arab world a core objective of his presidency. It is central to his efforts to disembowel al-Qaeda and neutralize the Iranian threat. He is not about to squander the opportunity the Arab Spring has provided him to advance those goals.
If all of that requires tough love toward Israel, that's the price Mr. Obama is willing to pay. There are more than 400 million people in the Arab world, and fewer than eight million in Israel. Besides, the Israelis must know that, if push comes to shove, Mr. Obama will be there - as he was in February when the United States vetoed a United Nations Security Council resolution declaring Israeli settlements in the West Bank "illegal."
But on Thursday, Mr. Obama also made it known that America, under his command, has changed. It was another sign that he is rewriting the prevailing presidential playbook on Israel. From Ankara to Anchorage, the world noticed - and waits for the next shoe to drop.
With a report from Daniel Leblanc in Ottawa