BEIRUT — Hezbollah's leader vowed Friday that his militants would keep fighting in Syria "wherever needed" after the U.S. agreed to arm the rebels in the civil war, setting up a proxy fight between Iran and the West that threatens to engulf more of the Middle East.
President Barack Obama has deepened U.S. involvement in the conflict, authorizing lethal aid to the rebels for the first time after Washington said it had conclusive evidence the Syrian regime had used chemical weapons. Syria accused Obama of lying about the evidence, saying he was resorting to fabrications to justify his decision to arm the rebels.
The opposition forces, which have suffered key battlefield losses in recent weeks and were facing heavy fighting Friday in Syria's largest city of Aleppo, appealed for the weapons to be sent to them as soon as possible to swing the momentum to their side.
The 2-year-old conflict, which the U.N. estimates has killed more than 90,000 people and displaced millions, is increasingly being fought along sectarian lines, pitting Sunni against Shiite Muslims, and is threatening the stability of Syria's neighbors.
Sheikh Hassan Nasrallah, chief of the Shiite Hezbollah group in Lebanon, appeared unwavering in his support for the regime of Syrian President Bashar Assad.
He signaled for the first time the Iranian-backed militant group will stay involved in the civil war after helping Assad's army recapture the key town of Qusair in central Homs province from rebels.
"We will be where we should be. We will continue to bear the responsibility we took upon ourselves," Nasrallah said in a speech via satellite to supporters in south Beirut. "There is no need to elaborate. ... We leave the details to the requirements of the battlefield."
Nasrallah appeared angry and defiant, saying the group has made a "calculated" decision to defend the Assad regime.
Hezbollah has come under harsh criticism at home and abroad for sending its fighters to Qusair, and Nasrallah's gamble in Syria primarily stems from his group's vested interest in the regime's survival. The Syrian government has been one of Hezbollah's strongest backers for decades, and the militant group fears that if Assad's regime falls, it will be replaced by a U.S.-backed government that is hostile to Hezbollah.
Nasrallah said his group was the last to join the fray in Syria, after hundreds and perhaps thousands of Sunni fighters — many of them from Lebanon — headed to Syria in support of the rebels.
Assad's forces, aided by the Hezbollah fighters, captured Qusair on June 5, dealing a heavy blow to rebels who had been entrenched in the strategic town for more than a year. Since then, the regime has shifted its attention to recapture other areas in the central province of Homs and the city of Aleppo in the north.
Nasrallah did not say outright whether his group would go as far north as Aleppo, but he strongly suggested the group was prepared to fight until the end.
"After Qusair for us will be the same as before Qusair," he said.
The Britain-based Syrian Observatory for Human Rights said the fighting in Aleppo was concentrated in the city's eastern rebel-held neighborhood of Sakhour, calling the fighting "the most violent in months." It said regime troops attacked the neighborhood from two directions but failed to advance, suffering casualties.
The Obama administration is still grappling with what type and how much weaponry to send to the Syrian rebels, but the announcement buoyed the opposition forces, which are heavily outgunned and outmanned.
The commander of the main Western-backed rebel group said he hoped that U.S. weapons will be in the hands of rebels in the near future.
"This will surely reflect positively on the rebels' morale, which is high despite attempts by the regime, Hezbollah and Iran to show that their morale after the fall of Qusair deteriorated," Gen. Salim Idris told Al-Arabiya TV.
U.S. officials said the administration could provide the rebels with small arms, ammunition, assault rifles and a variety of anti-tank weaponry such as shoulder-fired rocket-propelled grenades and other missiles. The officials spoke on condition of anonymity in order to discuss internal administration discussions with reporters.
Loay AlMikdad, a spokesman for the Free Syrian Army, said Idris will begin meeting with international representatives Saturday to work out the details of the weapons and their delivery.
"We encourage them to take a decision in this relation, by establishing a no-fly zone either all over Syria or areas they choose based on their technical or military considerations on the ground," he said, adding that would ensure safe areas for civilians.
"We hope they start arming immediately. Any delay costs blood of Syrians. It is not water, it is blood of the Syrians, women and children and its future," AlMikdad told The Associated Press. He said the rebels have asked for shoulder-fired rockets, anti-tank missiles, anti-aircrafts missiles, surface-to-surface missiles and armored vehicles.
The U.S. has made no decision on operating a no-fly zone over Syria, said Ben Rhodes, Obama's deputy national security adviser.
A Syrian opposition figure with wide knowledge of the situation in Syria said Friday that a French-Saudi operation to arm rebels has been underway along the Turkish-Syrian border for the past few days. He spoke on condition of anonymity for fear of retaliation.
The French government did not confirm the deliveries and an official with the French president's office said: "It's false."
The U.S. said Thursday it had conclusive evidence that Assad's regime has used chemical weapons, including the nerve agent sarin, on a small scale against opposition forces. The Syrian government dismissed the U.S. allegations Friday as "full of lies."
U.N. Secretary-General Ban Ki-moon said there can be no certainty of chemical weapons use in Syria without an on-the-ground investigation. Ban said he was opposed to the U.S. decision to arm the rebels, adding that increasing the flow of weapons to either side "would not be helpful."
At the United Nations, U.S. Ambassador Susan Rice told reporters that Washington is "very confident" in its assessment on Syria's use of chemical weapons.
"We've taken two months to reach this through a very careful and deliberative process," Rice said.
Obama's decision to arm the rebels is bound to heighten tensions with Russia, a staunch ally of Assad, and Moscow disputed the allegations about chemical weapons use by the Syrian regime.
Russian Foreign Minister Sergey Lavrov told U.S. Secretary of State John Kerry in a phone conversation Friday that the "accusations put forth by the United States to Damascus about the use of chemical weapons are not supported by trustworthy facts," a Russian Foreign Ministry statement said.
Lavrov told Kerry that stepping up U.S. involvement would be "fraught with escalation in the region," the statement added.
Earlier, President Vladimir Putin's foreign affairs adviser, Yuri Ushakov, said the information provided by U.S. officials to Russia "didn't look convincing."
Ushakov said there was no talk yet about whether Russia could retaliate to the U.S. move to supply weapons to the Syrian rebels by delivering the S-300 air defense missile systems to the regime.
Alexey Pushkov, chairman of Russia's parliamentary foreign affairs committee, wrote on his Twitter account Friday that "the data on Assad's use of chemical weapons were faked in the same place as the lie about (Saddam) Hussein's weapons of mass destruction," referring to the deposed Iraqi dictator.
"Obama is going down the route of G. Bush," he added, a reference to former President George W. Bush's assertion — never proven, but used to justify the invasion of Iraq — that Saddam Hussein possessed weapons of mass destruction.
Koray Caliskan, associate professor of political science at Bogazici University, said the U.S. decision to arm the rebels while Russia continues to militarize Syria "from top to bottom" will have dire consequences for Syria.
"Unfortunately this way would only destroy Syria until no one lives there," he said in Istanbul.
Turkey's state-run news agency said 73 Syrian military officers — including seven generals and 20 colonels — crossed the border into Turkey with their families "seeking refuge."
The Anadolu Agency said they arrived in the town of Reyhanli and were taken to a refugee camp that houses military officers who have defected from the Syrian army. Turkish Foreign Ministry officials and the local administrator in Reyhanli could not immediately confirm the report.