BEIRUT: As fighters with Lebanon’s Hezbollah movement wage the battles that are helping Syria’s regime survive, their chief sponsor, Iran, is emerging as the biggest victor in the wider regional struggle for influence that the Syrian conflict has become.

With President Obama set to host a White House meeting of top national security aides on Wednesday to reassess options in light of recent setbacks for the rebels seeking to oust Syrian President Bashar al-Assad, the long-term outcome of the war remains far from assured, analysts and military experts say.

But after the Assad regime’s capture of the small but strategic town of Qusair last week — a battle in which the Iranian-backed Shia militia played a pivotal role — Iran’s supporters and foes alike are mulling a new reality: that the regional balance of power appears to be tilting in favor of Tehran, with potentially profound implications for a Middle East still grappling with the upheaval wrought by the Arab Spring revolts.

“This is an Iranian fight. It is no longer a Syrian one,” said Mustafa Alani, director of security and defense at the Dubai-based Gulf Research Council. “The issue is hegemony in the region.”

The ramifications extend far beyond the borders of Syria, whose location at the heart of the Middle East puts it astride most of the region’s fault lines, from the Israeli-Palestinian conflict to the disputes left over from the U.S. occupation of Iraq, from the perennial sectarian tensions in Lebanon to Turkey’s aspirations to restore its Ottoman-era reach into the Arab world.

An Iran emboldened by the unchecked exertion of its influence in Syria would also be emboldened in other arenas, Alani said, including the negotiations over its nuclear program, as well as its ambitions in Iraq, Lebanon and beyond.

“If Iran wins this conflict and the Syrian regime survives, Iran’s interventionist policy will become wider and its credibility will be enhanced,” he added.

From Iran’s point of view, sustaining Assad’s regime also affirms Iran’s control over a corridor of influence stretching from Tehran through Baghdad, Damascus and Beirut to Maroun al-Ras, a hilltop town on Lebanon’s southern border that offers a commanding view of northern Israel, according to Mohammad Obaid, a Lebanese political analyst with close ties to Hezbollah.

Iran has sought to minimize its visible involvement in Syria so as not to exacerbate sectarian tensions that have been inflamed by a conflict pitting an overwhelmingly Sunni opposition against a regime dominated by Assad’s minority Shiite-affiliated sect, Obaid said.

Iran has provided advice, money and arms to Assad’s regime, but the manpower needed to bolster his forces, flagging after two years of trying to contain the revolt, has come from Hezbollah, which was founded in the 1980s with help from Iran’s Revolutionary Guard Corps and has become Lebanon’s leading military and political force.

“Hezbollah is part of the Iranian strategy,” Obaid said. “This counts as a victory for the group of Iran, Syria, Iraq and Hezbollah against the group backed by the United States.”