Kuwait rarely rebuffs its ally, the United States, partly out of gratitude for the 1991 Persian Gulf War. But in October it reneged on a pledge to send three military observers to an American-led naval exercise in the Gulf, according to U.S. officials and Kuwaiti analysts.
"We understood," a State Department official said. "The Kuwaitis were being careful not to antagonize the Iranians."
Four years after the United States invaded Iraq, in part to transform the Middle East, Iran is ascendant, many in the region view the Americans in retreat, and Arab countries, their own feelings of weakness accentuated, are awash in sharpening sectarian currents that many blame the United States for exacerbating.
Iran has deepened its relationship with Palestinian Islamic groups, assuming a financial role once filled by Gulf Arab states, in moves it sees as defensive and the United States views as aggressive. In Lebanon and Iraq, Iran is fighting proxy battles against the United States with funds, arms and ideology. And in the vacuum created by the U.S. overthrow of Iranian foes in Afghanistan and Iraq, it is exerting a power and prestige that recalls the heady days of the 1979 Islamic revolution, when Iranian clerics led the toppling of a U.S.-backed government.
"The United States is the first to be blamed for the rise of Iranian influence in the Middle East," said Khaled al-Dakhil, a Saudi writer and academic. "There is one thing important about the ascendance of Iran here. It does not reflect a real change in Iranian capabilities, economic or political. It's more a reflection of the failures on the part of the U.S. and its Arab allies in the region."
Added Eyal Zisser, head of the Middle Eastern and African Studies Department at Tel Aviv University in Israel: "After the whole investment in democracy in the region, the West is losing, and Iran is winning."
The United States has signaled a more aggressive posture toward Iran. President Bush on Friday defended a Pentagon program to kill or capture Iranian operatives in Iraq. Vice President Cheney, in a Newsweek interview published Sunday, said the deployment of a second U.S. aircraft carrier task force to the Persian Gulf was intended to signal to the region that the United States is "working with friends and allies as well as the international organizations to deal with the Iranian threat."
And John D. Negroponte, outgoing director of national intelligence, told Congress this month that Iran's influence is growing across the region "in ways that go beyond the menace of its nuclear program."
Iranian officials -- emboldened but uneasy over nuclear-armed neighbors in Israel and Pakistan and a U.S. military presence in the Gulf, Iraq and Afghanistan -- have warned that they would respond to an American attack on Iran's facilities.
"Iran's supporters are widespread -- they're in Iraq, they're in Afghanistan, they're everywhere. And you know, the American soldiers in the Middle East are hostages of Iran, in the situation where a war is imposed on it. They're literally in the hands of the Iranians," said Najaf Ali Mirzai, a former Iranian diplomat in Beirut who heads the Civilization Center for Iranian-Arab Studies. "The Iranians can target them wherever, and Patriot missiles aren't going to defend them and neither is anything else."
"Iran would suffer," he added, "but America would suffer more."
As that struggle deepens, many in the Arab world find themselves on the sidelines. They are increasingly anxious over worsening tension between Sunni and Shiite Muslims across the Middle East, even as some accuse the United States of stoking that tension as a way to counter predominantly Shiite Iran. Fear of Iranian dominance is coupled, sometimes in the same conversation, with suspicion of U.S. intentions in confronting Iran.
"It was necessary to create an enemy to justify the failure of the American occupation in Iraq," Talal Salman, the editor-in-chief of as-Safir, a Lebanese newspaper, wrote in a column this month. "So to protect ourselves against the coming of the wolf, we bring the foreign fleets that fill our lands, skies and seas."
Iranian rivalry with its Sunni Arab neighbors is centuries old, but as with most conflicts in the Middle East, its modern contours are shaped by politics and interests.
Iran has found itself strengthened almost by default, first with the U.S.-led invasion of Afghanistan to Iran's east, which ousted the Taliban rulers against whom it almost went to war in the 1990s, and then to its west, with the American ouster of Iraqi President Saddam Hussein, against whom it fought an eight-year war in the 1980s.
Arab rulers allied with the United States issued stark warnings. Jordan's King Abdullah in 2005 spoke darkly of a Shiite crescent that would stretch from Iran, through Iraq's Shiite Arab majority, to Lebanon, where Shiites make up the largest single community. President Hosni Mubarak of Egypt suggested last year that Shiites in the Arab world were more loyal to Iran than to their own countries. And in a rare interview, published Saturday, King Abdullah of Saudi Arabia suggested that Iran, although he did not name the country, , was trying to convert Sunni Arabs to Shiism. "The majority of Sunni Muslims will never change their faith," he told al-Siyassah, a Kuwaiti newspaper.
Across the region, Iran has begun to exert influence on fronts as diverse as its allies: the formerly exiled Shiite parties in Iraq and their militias; Hezbollah, a Lebanese group formed with Iranian patronage after Israel's 1982 invasion; and the cash-strapped Sunni Muslim movement of Hamas in the Palestinian territories.
"I disagree with Iranian policy, but you have to give the Iranians credit," said Abdullah al-Shayji, a political science professor and head of Kuwait University's American Studies Unit. "You have to appreciate that they have an agenda, they're planning for it, they seize the opportunity, they see an American weakness and they are capitalizing on it."
A helping hand
In Beirut's southern suburbs, a Hezbollah stronghold, a banner hangs near a bridge wrecked by Israeli strikes last summer: "The Zionist enemy destroys, the Islamic Republic of Iran builds." Even before the 33-day war ended, Iran had provided Hezbollah $150 million to begin rebuilding, some of it going to victims in $10,000 bundles of crisp U.S. currency, according to a Shiite politician who spoke on condition of anonymity.
"You want me to give you my opinion? Honestly?" asked Hajj Hassan Sbeiti, a 44-year-old merchant, his face breaking into a wry smile. "If you say hello to me, you probably like me. If you say hello to me and ask what I need, you're a friend. If you say hello to me, ask what I need and put money in my hand, then you're going to be my brother."
In Iraq, U.S. officials say Iran is providing Shiite militias with sophisticated projectiles capable of penetrating U.S. armored vehicles and backing those forces in a gathering civil war against Sunni Arabs. One commander of the Mahdi Army, a Shiite militia that U.S. military officials now identify as the greatest security threat in Iraq, said that however much he might dislike Iran, he was eagerly anticipating the delivery of 50 rocket-propelled grenades to Basra.
But no less influential are the ties that Iran has deepened with the three main Shiite groups in Iraq, some of whose leaders spent years in exile in Iran and are now nominally allied with the United States, and the burgeoning economic relationship between the two countries.
The extent of Iran's engagement in the Arab world, and the rising sectarianism that has accompanied the Iranian ascendance, troubles Arabs who already worry about growing tension between the United States and Iran.
"If Iran is bombed, Iran's reaction is a sure thing. They cannot sit idle and what kind of reaction they will take is a big question," said Abbas Bolurfrushan, the president of the Iranian Business Council in Dubai, a booming city-state on the Gulf that is part of the United Arab Emirates, where an estimated 400,000 Iranians live and work.
The result? "A disaster," he said, "disaster."
Mirzai, the former Iranian diplomat, offered a similar scenario in more threatening terms. Wearing a white turban and the robes of a cleric, he sketched out potential Iranian responses: cutting the Strait of Hormuz in the Persian Gulf, through which 20 percent of the world's oil passes; retaliation in Iraq, Afghanistan or Lebanon; attacks on U.S. targets in the Gulf.
"There is a policy the Iranians have and they've repeated it often -- the Gulf is either safe for everyone or no one," he said.
In an attempt to contest Iran's influence, the United States has sought to form an axis among Sunni Arab states it considers moderate: Egypt, Jordan, Saudi Arabia and smaller countries in the Gulf. Israeli officials have spoken about a possible alignment of their country's interests with those states to arrest both Iran's influence and its nuclear program.
In November, Israeli Prime Minister Ehud Olmert said he would try to deepen ties with those states, some of which have yet to recognize Israel, in what Israeli analysts saw as an opening bid to create an anti-Iranian bloc.
But Zisser, of Tel Aviv University, cautioned that "all of these countries are not very strong, and they have their own problems."
"Iran's threat could do something to bring them together, but I would say that any alliance that comes out of it would be defensive in nature," he said. "These countries are not going to be able to unite in any way that would meaningfully change the face of the Middle East."
Potentially more far-reaching is the sectarian tension that the struggle has ignited. In the Palestinian territories, Israeli officials say, Iran has been increasingly successful in influencing the chaotic political situation, particularly by funding the Hamas-led government.
The connection has not gone unnoticed in the Palestinian street. At two rallies this month for Fatah, the movement led by Palestinian Authority President Mahmoud Abbas, crowds directed chants at Hamas, a Sunni Arab group. "Shiites, Shiites," they shouted.
Across the Middle East, once antiquated words have sprung up in conversations about Shiites -- Safawis, for instance, drawn from the name of a Persian empire that brought Shiism to Iran. In Lebanon, posters have gone up in Sunni neighborhoods portraying leaders united by little other than their Sunni sectarian affiliation: Saddam Hussein, Yasser Arafat, Rafiq al-Hariri, the former Lebanese prime minister killed in a 2005 car bombing, and Sheik Ahmed Yassin, the leader of Hamas who was assassinated by Israel in 2004.
"You are in heaven," the poster reads, "and those who killed you will go to hell."
Iranian officials have repeatedly warned against the phenomenon, fearing it will curb their leverage in an Arab street that remains majority Sunni. Many in the Arab world watch its gathering force with a sense of helplessness.
"It's very bleak and it's very dangerous," said Dakhil, the Saudi writer. "We have a sectarian civil war in Iraq now and this is drawing sectarian lines through the region. This is the most important, the most dangerous ramification of the American war in Iraq."
Correspondent Scott Wilson in Jerusalem contributed to this report.