ISTANBUL, Turkey, Aug. 9 (UPI) -- The Turkish government says it has intercepted an arms shipment from Iran headed for Tehran's key ally Syria, where the regime is battling to crush a 5-month-old uprising in which an estimated 1,700 protesters have been killed.
Tehran is widely reported to be providing military aid and counterinsurgency specialists, as well as economic support, to the minority Alawite regime of Syrian President Bashar Assad.
Iran has a lot at stake in Syria as the Tehran leadership drives to become the region's paramount power and give Islam's breakaway Shiite sect ascendancy over the traditionally dominant mainstream Sunnis.
Syria is Iran's strategic gateway to the Levant and Israel's borders and Tehran can be expected to do everything it can to ensure that Assad's regime survives.
Western and Arab intelligence officers say Iran's Revolutionary Guards, headed by its elite and covert al-Quds Force, has taken over supervision of the campaign to suppress Syria's opposition forces.
Tehran denies involvement in the Syrian bloodletting but the European Union as well as the U.S. administration have imposed sanctions against the Revolutionary Guard leadership and some Syrian commanders because of the crackdown.
Indeed, Syria, with its Sunni majority, has become a proxy battleground for Iran and its main Arab rival, Saudi Arabia. They're vying for supremacy in the region and what transpires in Syria could have a deep and far-reaching impact on the geopolitics of the Middle East.
"Were a Sunni Arab regime with closer ties to Riyadh to take the place of the Alawite minority government in Damascus, the loss to Tehran's regional influence would be profound," observed the U.S. security consultancy Stratfor in an analysis last week.
"While Saudi Arabia has not actively sought the topple the Syrian regime, Syria's present crisis presents an opportunity for Saudi Arabia to turn back the gains Iran has made since 2003 -- though Tehran can be expected to put considerable resources toward ensuring the Syrian regime's survival."
Sunni-majority Turkey is also increasingly critical of the Assad regime's escalating suppression campaign, spearheaded by trusted Alawite units of the army and the intelligence services.
Turkish Foreign Minister Ahmet Davutoglu confirmed Friday that a truck carrying weapons from Iran to Syria had been intercepted and was being held by security authorities. He gave no other details.
The weapons could be intended for Hezbollah, the Lebanese Shiite militia supported by Iran and Syria as have other shipments sent by Tehran in recent years.
Hezbollah, too, has been reported to be aiding its Syrian allies to put down the uprising. Hezbollah denies that but both stand to lose heavily if the Assad dynasty, which with Tehran has nurtured Hezbollah since it was founded after Israel's invasion of Lebanon in 1982, should fall.
Turkish media reported in mid-April that several alleged Iranian arms shipments bound for Syria had been seized in trucks on several routes in southern Turkey. In the preceding months other arms shipments had been seized aboard aircraft and trains by Turkish authorities.
Western intelligence services suspect that other shipments have been moved through Iraq, which lies between Iran and Syria, and via transshipment points as distant as Venezuela, where Iran has been building links.
Diplomats say recent seizures by the Turks, and heightened surveillance at border crossings, underline Ankara's growing unease with the violent suppression of protests in Syria and the machinations of Iranian agents in Turkey.
This may complicate Iran's operations to save Assad from being overthrown but it isn't likely to stop Tehran fighting tooth and nail to prevent the collapse of its 30-year strategic alliance with Syria, forged by Assad's late father and predecessor, Hafez Assad.
The Americans have sought for years to break the Tehran-Damascus partnership since it emerged in 1980, primarily to weaken Iran.
But in the Middle East, where alliances between Arab states since World War II have invariably collapsed because of traditional dynastic rivalries, the bonds between Iran and Syria have endured.
These relations, based on deep hostility toward the United States and Israel, show no sign of unraveling.
Tehran's overriding priority is domestic stability and if the Damascus regime collapses, the fear is that clerical rule in Iran would be seriously threatened as well, as it was after the disputed 2009 elections.