Unrest roiling Syria, a linchpin state in the Middle East, is shaking the region in ways that even the revolution in Egypt did not, threatening to upend some longstanding alliances and encouraging neighbors to scramble for sudden advantage.
Already, the chaos in Syria is showing the potential to affect issues as broad as Iran's conflict with the U.S. and its allies, and as narrow as regional water rights.
Whether or not President Bashar Assad weathers the storm, the uprising is forcing countries in the region to formulate a response and may ultimately change the balance of power.
While few expected the revolt against Egyptian President Hosni Mubarak early this year to dramatically shift his country's generally pro-Western policies, Syria maintains a wider range of contacts with countries that include Iran and Russia. For decades, it has been a key player in volatile Lebanon.
It has its own unresolved dispute with Israel over the Golan Heights, but is also important to Israel and the United States because of its alliance with Iran and Hezbollah, a relationship that both American and Israeli officials have encouraged Assad to break.
Iran has been chalking up diplomatic victories as pro-U.S. Arab regimes such as Mubarak's have either fallen or been challenged by democratic movements this year. But now that trouble has come to Syria, Tehran has suddenly cooled to the Arab Spring.
Syria serves as a political and military conduit for Iranian-backed militant groups in the eastern Mediterranean, including Hezbollah in Lebanon and Hamas in the Palestinian territories. Regime change in Syria could deliver a cataclysmic blow to Iran's ability to project power in the region and threaten Israel.
"We are worried about the resistance against Israel," said Asad Zarei, a pro-government political analyst in Tehran. "If the changes in Syria happen in a way that the resistance is undermined, we are very worried."
Syrian authorities, facing their greatest security challenge in 30 years, continued an assault Tuesday on the southern city of Dara, where they had dispatched tanks and thousands of troops the day before. Troops who had cut off electricity and phone networks in an attempt to smother the protest movement reportedly opened fire on civilians.
Despite the intensity of the crackdown, protests were reportedly held in several cities. Witnesses said about 50 doctors held a demonstration in Aleppo demanding the release of all medical personnel and students arrested in recent weeks.
Over the weekend, as Syrian security forces mowed down scores of peaceful protesters in cities around the country, Iranian state media and prayer leaders cried out against oppression and injustice in a different Arab nation — Bahrain, which like Iran has a Shiite Muslim majority.
"Iran cannot remain silent in the face of the atrocities in Bahrain," supreme leader Ayatollah Ali Khamenei said Saturday. Khamenei said nothing about the carnage in Syria. Iranian state television reported that the protests had left 280 injured — all of them Syrian police officers.
Commentators in Arab countries suspicious of Iran's regional ambitions gloated over Tehran's obvious discomfort — supporting uprisings against secular regimes across the Arab world except the rebellion in Syria, which it insists is the result of a Zionist plot.
"Iran and Hezbollah destroyed whatever credibility Iran has left, when Iran let down the people of Syria by considering the movement of the people there a conspiracy," Hilmi Asmar wrote in the April 20 edition of Al Dustour, a Jordanian daily.
Some Iranians appear to be realizing that the government's official position is untenable, and are calling on Damascus to reform. "The Syrian regime should heed the demands of people in Syria and manage the current crisis in the country," former Iranian Foreign Minister Manoucher Mottaki was quoted as telling students Tuesday.
Countries close to Syria, such as Turkey, have responded by distancing themselves from the Assad clan. Syria has encouraged Turkey's increasingly assertive regional leadership in recent years because of its importance as a trade partner, its potential as a counterweight to the West and as an alternative to the relationship with Iran.
Turkish Prime Minister Recep Tayyip Erdogan, who was harshly critical of Mubarak, has long been a friend of Assad. He told a news conference Tuesday that Turkey was displeased by events in Syria. "During my conversation with Assad, I have conveyed our concern to him," he said, according to the semiofficial Anatolia news agency. "We do not desire an antidemocratic approach in Syria."
Syrian opposition figures and Turkish democracy activists appeared together Tuesday on Al Jazeera television live from Istanbul, Turkey's largest city, condemning Assad's regime.
"Why is Bashar killing his brothers?" a Turkish activist said during the program. "Is it because they want to live a free and dignified life?"
Lebanon's political factions are carefully watching events unfold in their influential neighbor, which occupied Lebanon for decades. Syria strongly backs some Lebanese factions, including Hezbollah, while others consider themselves blood enemies of Damascus. Any change of political orientation in Syria could dramatically change Lebanon's balance of power.
Countries may also see an opportunity in Damascus' weakness. Neighboring Jordan recently decided to demand renegotiation of a water-sharing agreement from a river that traverses both nations.
"The amount of water in the Yarmuk River is constantly dropping; therefore, the agreement needs to be reconsidered," water authority official Saad Abu-Hammur told the Jordan Times on April 16, a day after widespread protests rocked Syria.
Analysts say Saudi Arabia may be considering using its diplomatic and political influence to offer Assad a way out of his predicament, but for a price: breaking his alliance with Iran, which is accused of stirring up trouble among Shiite minorities in countries such as Bahrain and Saudi Arabia.
"Watch to see if Syrian Foreign Minister Walid Moallem suddenly takes a trip to Riyadh," said one analyst in Beirut, who spoke on condition of anonymity.
The foreign minister of the pro-Saudi United Arab Emirates, Abdullah bin Zayed al Nahyan, met Sunday with Syrian officials in what one analyst described as a possible prelude to a rapprochement with Saudi Arabia.
On offer might be help slowing the flow of information feeding the revolt on the streets of Syria. The UAE hosts Saudi-owned Al Arabiya, one of two Arabic-language channels whose reporting has been inflaming passions across Syria, and owns the Thuraya satellite phone network used by pro-democracy activists to circumvent the secret police.
Other than possibly toning down news coverage, it remained unclear how much influence Saudi Arabia and its Arabian Peninsula allies, or anyone else, may have on events in Syria, which appear to have taken on a life of their own.
Muhanna said he didn't think the Saudis wanted to see a revolution in Syria, which could usher in a more radical regime.
"If they want to appear to be giving support to the Assad regime, it could help," he said. "It could quell more radical Islamic activists."
Special correspondents Ramin Mostaghim in Tehran and Meris Lutz and Roula Hajjar in Beirut contributed to this report.