Citing U.S. Fears, Arab Allies Limit Aid to Syrian Rebels Manu Brabo/Associated Press Denied more weapons like shoulder-fired missiles, Syrian rebels rely on rifles like this Kalashnikov, or AK. "You can't stop the Syrian regime's military with AKs," a state official in Qatar said. RIYADH, Saudi Arabia - For months, Saudi Arabia and Qatar have been funneling money and small arms to Syria's rebels but have refused to provide heavier weapons, like shoulder-fired missiles, that could allow opposition fighters to bring down government aircraft, take out armored vehicles and turn the war's tide. While they have publicly called for arming the rebels, they have held back, officials in both countries said, in part because they have been discouraged by the United States, which fears the heavier weapons could end up in the hands of terrorists. As a result, the rebels have just enough weapons to maintain a stalemate, the war grinds on and more jihadist militants join the fray every month. "You can give the rebels AKs, but you can't stop the Syrian regime's military with AKs," said Khalid al-Attiyah, a state minister for foreign affairs in Qatar. Providing the rebels with heavier weapons "has to happen," he added. But first we need the backing of the United States, and preferably the U.N. Saudi officials here said the United States was not barring them from providing shoulder-fired missiles, but warning about the risks. The Saudis and Qataris said they hoped to convince their allies that those risks could be overcome. "We are looking at ways to put in place practices to prevent this type of weapon from falling into the wrong hands," one Arab official said, speaking on the condition of anonymity in line with diplomatic protocol. American support for such weapons transfers is unlikely to materialize any time soon. The Obama administration has made clear that it has no desire to deepen its efforts, mostly providing logistical support for the rebels. Administration officials would not comment on what they are telling their Persian Gulf allies about arming the rebels. "We are doing what we feel is appropriate to help the unarmed opposition to be more effective and working closely with the opposition to prepare for a transition," the State Department said in response to a question on the subject. Backing from the United Nations Security Council, where any intervention is blocked by the firm vetoes of Russia and China, seems even less likely. Nor is the call for an Arab-led military action in Syria, voiced two weeks ago by the emir of Qatar at the United Nations General Assembly, expected to bear fruit. Many Saudi and Qatari officials now fear that the fighting in Syria is awakening deep sectarian animosities and, barring such intervention, could turn into an uncontrollable popular jihad with consequences far more threatening to Arab governments than the Afghan war of the 1980s. "If the killing continues, the youth will not listen to wise voices," said Salman al-Awda, one of this country's most prominent clerics, in an interview at his office here. They will find someone who will encourage them, and they will go. Already, there are signs of an uptick in the number of young men crossing illegally into Syria from Saudi Arabia and other Muslim countries, and of private fund-raising efforts across the gulf to help the rebels acquire heavier weapons. The fighting has also spilled into Turkey, which shelled Syria for four days last week after a Syrian shell killed five Turkish civilians. Saudi Arabia has long had an antagonistic relationship with the government of President Bashar al-Assad in Syria, and sees itself as the protector of Syria's Sunni majority in a country governed by Mr. Assad's Alawite minority. But the prospect of an increasingly sectarian civil war in Syria is deeply troubling to many here, where the Afghan jihad spawned a generation of battle-tested zealots who returned home and waged a bloody insurgency that was brought under control only recently. "The government really doesn't want to repeat the experience we had with the guys who went to Afghanistan and Iraq," said Mshari al-Zaydi, a Saudi columnist and an expert on jihadi movements. The damage from Al Qaeda was worse in Saudi Arabia than it was in the U.S.A. In May, a group of conservative Saudi clerics, including some who had called for volunteers to fight in Iraq, announced a fund-raising drive on Facebook to support the Syrian rebels. Days later, they posted messages saying the government had barred them from sending donations. Some clerics criticized the government's restriction, including Mr. Awda, who sent an apparent warning on Twitter: "The donations to Syria cannot be limited to this route or that route, and those who want to provide support will find a way." Michael R. Gordon contributed reporting from Washington.