BEIRUT — The interim accord hammered out between Iran and global powers focuses narrowly on Tehran's nuclear ambitions but the reaction across the Middle East points to a broader significance: the prospect of a geopolitical shift with repercussions across the region.

The process is still embryonic and may go nowhere. But the Middle East is already abuzz with speculation about a thaw between Washington and Tehran emerging from the Geneva talks. Some analysts say it may turn out to be a "hinge" moment that — however gradually — alters the political landscape of the highly volatile region.

"This is already being seen as a kind of game-changer," said Paul Salem, an analyst at the Middle East Institute, a Washington-based think tank. "This is not just about how much uranium is being enriched or when. It's about a new alignment and its potential impacts in Syria, in Iraq, in Lebanon, in all the regional arrangements."

Condemnation from Israel and angry silence from Saudi Arabia — both key U.S. allies and avowed enemies of Tehran — highlight a profound disquiet about much more than the letter of the preliminary six-month nuclear accord.

Antagonism between Iran and the U.S. has been a major factor in the region's web of alliances for more than three decades.

Saudi officials view their kingdom and its allies as being engaged in a colossal struggle for regional influence between Islam's two great branches.

The Sunni-dominated Persian Gulf kingdoms accuse Shiite Iran of meddling from Syria to Lebanon to Bahrain. Riyadh plainly would prefer to see Iran consigned indefinitely to membership in an "axis of evil" than engaged in direct and seemingly amiable negotiations with the U.S. secretary of State at a five-star Geneva hotel.

"It is clear that the traditional Arab allies of the U.S. in the region, the Saudis specifically but also the Jordanians, are shocked by this American transformation," said Fahed Khitan, an Amman, Jordan-based political analyst. "The Saudis and the Israelis are, perhaps for the first time, in a camp together."

While Saudi officials have kept their ire private so far, Israeli authorities have publicly denounced the preliminary nuclear accord with Iran as a "bad deal" and "historic mistake," in the words of Prime Minister Benjamin Netanyahu.

From Israel's perspective, Iran is a challenge on many fronts, including in Lebanon, which shares a tense border with Israel that is patrolled by United Nations peacekeepers. Iran's Lebanese ally, Hezbollah, has a powerful military force and tens of thousands of rockets that it can use to target Israel.

In Israel, there has been media speculation that Netanyahu would derail the latest U.S.-backed initiative for peace between Israel and the Palestinians in retaliation for the Iran nuclear accord.

Any change in U.S.-Iran relations will be gradual, diplomats say. U.S. officials have been at pains to emphasize their sensitivity to their allies' misgivings. Upon announcing the terms of the nuclear deal, Secretary of State John F. Kerry went out of his way to stress that the accord did not necessarily augur a broader reconciliation.

"It is fair to say that Iran's choices have created a very significant barrier, and huge security concerns for our friends in the region, for Israel, for gulf states and others," Kerry told reporters in Geneva. "Obviously, one would hope that Iran will make choices ... to rejoin the community of nations in full. The first step is to resolve the nuclear issue."

U.S. officials have been careful in discussing wider regional implications. They've stressed that even while opening up this new diplomatic channel, they have kept the conversation focused narrowly on the nuclear issue — both in the public multinational negotiations and a series of secret bilateral talks between U.S. and Iranian diplomats. Other thorny issues such as Iran's support for Hezbollah were not discussed, according to a senior administration official who asked not to be identified when speaking about the negotiations.

Still, Kerry publicly shot down the idea still embraced in some circles — including among Obama administration critics in Congress — that piling on more economic sanctions will lead to the collapse of the Islamic Republic.

"Some might say we should simply continue to increase pressure — just turn up the screws, continue to put sanctions on, and somehow that's going to push Iran toward capitulation or collapse," Kerry said, adding: "Not by any interpretation that we have from all the experts."

Though often described in the West as isolated, Iran has in fact cultivated a regional sphere of influence extending from Lebanon to Syria and Iraq. To the east, Iran has also sought to foster ties with the government of Afghan President Hamid Karzai in contrast to its hostile relationship with the Taliban.

It is close to the Shiite-dominated government of Iraqi Prime Minister Nouri Maliki that emerged after the U.S.-led invasion ousted Saddam Hussein, long Tehran's nemesis. Despite criticism of what many see as Maliki's autocratic style of leadership, the Obama administration has signaled its intent to increase military aid to Baghdad to help Maliki counter Sunni militants.

The difficult case of Syria — where Iran and Saudi Arabia are major players in a proxy war — may give some indication of whether a broader reconciliation between the West and Iran is on the horizon.

Tehran has supplied large amounts of financial and military aid to help keep Syrian President Bashar Assad in power, drawing sharp criticism from Washington. Saudi Arabia and its allies, including the United States, have backed rebels fighting to oust Assad.

On Monday, United Nations officials said it was not yet clear whether Iran would be invited to U.N.-backed Syrian peace negotiations scheduled for Jan. 22. But a senior Obama administration official cast doubt on Iran's participation.

The parties at the table in the upcoming Syria talks must agree to support the transfer of power from Assad's government to a transitional executive authority, language the U.S. interprets as a call for Assad to step down. The U.S. is not expecting Iran to agree to those terms, the official said.

Iran seems unlikely to abandon Assad and let Syria slip from its orbit. But as Western goals shift to stabilizing Syria from a threat of Al Qaeda-linked Sunni militants, some observers say Tehran could help to shape a new transitional government.

"If the West can talk to Iran about such a hugely sensitive issue such as Iran's own nuclear program, then I'm sure they can talk about what a transition might look like in Syria," said Salem. "Whether the talks will work or not is another matter. But I can certainly see them talking."

patrick.mcdonnell@latimes.com

Times staff writer Kathleen B. Hennessey in Washington and special correspondent Nabih Bulos in Amman contributed to this report.