JERUSALEM — American officials have confirmed that Israeli warplanes struck a convoy deep inside Syria that was believed to be carrying sophisticated anti-aircraft weaponry to the Hezbollah militia group in Southern Lebanon.

As common here, Israeli officials refused to affirm or deny the assertion, but Syria's military command denied any attack on a convoy, claiming that Israeli air force jets struck a military research center near the capital city of Damascus on Wednesday at dawn Syria's military command.

The attacks have raised fears the Syrian crisis is spreading elsewhere in the region.

The nature of the strikes and its exact location were equally unclear, The Washington Post reported, noting some reports saying a convoy carrying weapons had been hit, while others, such as Syrian state media, claimed the target was near Damascus. Lebanon on Wednesday said its airspace had been violated by Israel several times. 

Syrian rebel groups claimed the research center was in fact a known chemical weapons development site and posted a video allegedly showing a series of blasts shortly after the attack occurred. The video could not be authenticated. Also Wednesday, several rebel leaders claimed that they had attacked the site with mortar shells.

Israel's news site Ynet said Israeli intelligence had been aware of the military research center for decades. “Some of the center's studies have been presented as civilian in nature,” the site wrote.

"It’s a secret governmental body that answers directly to [Syrian President Bashar al] Assad and aggregates all of Syria's military research institutes," said Yiftah Shafir of the Jaffee Center for Strategic Studies in Tel Aviv.

The US official who confirmed the strike on the convoy also said Israel had informed the American government of the operation.

The White House warned Syria not to transfer weapons to Hezbollah. "Syria should not further destabilize the region by transferring weaponry to Hezbollah," AFP reported Deputy National Security Advisor Ben Rhodes as saying.

The beleaguered Syrian government wants to deflect attention from talk of missile transfers to terror groups on Lebanese soil, which some believe could open it to more international condemnation and possible international intervention.

Portraying the incursion as an unprovoked Israeli attack on its territory fits into Assad’s attempt to discredit the rebels with claims of their association with Israel.

Israel's Channel 10 news reported Wednesday night that the Syrian government said the rebels receive “Israeli-made rations."

The incursion comes at a moment of growing regional tensions. Iranian officials warned last week that any international military intervention in Syria would be viewed as an attack on Iranian sovereignty. On Sunday, Israel's cabinet discussed the danger Syrian chemical weapon caches may be transferred to Hezbollah and installed in two Iron Dome anti-missile batteries on its northern border.

Ali Akbar Velayati, an aide to Iran’s supreme leader Ayatollah Ali Khamenei, said “Syria plays a very key role in supporting or, God forbid, destabilizing the resistance front. For this same reason, an attack against Syria is considered an attack on Iran and Iran’s allies.”

Syria's few remaining allies responded to the air-force strike with strong language today. The Russian Foreign Ministry said in a press release that "If this information is confirmed, then we are dealing with unprovoked attacks on targets on the territory of a sovereign country, which blatantly violates the UN Charter and is unacceptable, no matter the motives to justify it."

Egypt's Foreign Minister Mohamed Kamel Amr slammed Wednesday's airstrike saying "such an assault on Arab land is entirely rejected and represents a flagrant violation of the United Nations Charter and international law."

Iranian Foreign Minister Ali Akhbar Salehi was reported by the state-run channel PressTV as saying the attack was "clearly coordinated with the West."

"This was an attempt to subvert the victories of the government over the rebels in Syria," he said, adding that it reveals cooperation between the rebels and the "Zionist regime."

Salahi's deputy Hossein Amir-Abdollahian warned in more ominous tones that the "Israeli bombing in Syria will have grave consequences on Tel Aviv."

Lebanese Foreign Minister Adnan Mansour demanded that the Arab world "confront Israel in every possible legal way," calling the airstrike "blunt aggression that we strongly condemn."

Israel appears to be betting that the Syrian government, tottering after a brutal 18-month rebellion, won’t respond militarily to the incursion, which many believe to have been a warning against attempts to safeguard Syrian munitions or chemical weapons on Lebanese soil.

However, Syria's ambassador to Lebanon Ali Abdul Karim Ali warned on Hezbollah TV that his country retains the ability to implement "a surprise decision to Thursday morning respond to the aggression of the Israeli warplanes.”

“Syria is engaged in defending its sovereignty and its land," he added.

Upping the ante, Iran on Thursday informed the UN's International Atomic Energy Agency of its intention to speed up its production of enriched uranium. The statement, which appeared to be directed at the United States, Israel and Europe, comes as Iran has refused to commit to ongoing talks with the West on its nuclear program.

Israeli Foreign Ministry spokesman Yigal Palmor and Israel Army spokesman Captain Eytan Buchman both declined to comment on the incursion and on the Syrian and Iranian threats.

Palmor said "Israel continues to respond with resounding silence."

"The Iranian government is very worried,” says Iran expert Meir Javedanfar of the Interdisciplinary Center in Herzliya. “It set a red line about any foreign involvement in Syria and it took Israel less than a week to cross that red line."

Israel should be concerned about the Iranian threat, he said, “however I don't think the chances are high."

Others agree. "I don't think there's a significant difference in the threat level due to what may have happened in the last 24 hours on the Syrian border,” said Gerald Steinberg, a political science professor at Bar Ilan University. “Iranian leadership often talks tough, but in general avoids confrontation."

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With the impending loss of its close ally Assad, he said, Iran now finds itself "in a particularly weak position right now."

Some 60,000 people are estimated killed in months of brutal warfare between Syrian President Bashar al-Assad and the armed uprising against his rule.

Meanwhile, Israel and other Western countries are concerned that Assad is making use of the country's chemical weapons stockpile. 

International efforts to end the crisis in Syria, where the United Nations says at least four million people now lack food and shelter due to the violence, have not been successful.

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