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Syrian rebels said Friday that newly arrived shipments of heavy weaponry could swing the momentum on the battlefield in their favor, after a shift in U.S. policy opened the door for others to send them arms.

Weapons from the United States have not materialized since the White House announced last week that it had authorized direct military support for the opposition, but the U.S. decision appears to have prompted other nations to increase their assistance, with new deliveries including highly prized antitank and antiaircraft weaponry, according to Khalid Saleh, a spokesman for the main Syrian Opposition Coalition.

Saleh declined to provide specifics but said shipments had come from countries in the Friends of Syria Group, a coalition of 11 Western and Arab nations that back the opposition. The group is due to meet in the Qatari capital, Doha, on Saturday to discuss coordinating military support for the rebels.

“It’s not all the advanced weapons that we’ve asked for, but it is a few that mean we will be able to respond to attacks by air and tanks,” Saleh said, linking their arrival to the White House decision. “The U.S. changing its position sends a very strong signal to the other countries,” he said.

CIA operatives and U.S. Special Operations troops have been secretly training selected rebel groups to use antitank and antiaircraft weapons in Jordan and Turkey since late last year, according to a report in the Los Angeles Times on Friday. The Pentagon and the CIA declined to comment on the report.

Timeline: Major events in Syria’s tumultuous uprising that began in March 2011.

Five rebel commanders, defectors from President Bashar al-Assad’s regular army who now lead battalions in southern Syria, said this week that they had attended or were familiar with training camps in Jordan run by what they described as U.S. intelligence officers and U.S. military officers.

The courses, which lasted a week to 10 days, involved some light-weapons training and tactics, the commanders said. They said they did not observe any instruction in the use of antitank or antiaircraft weapons.

“We have AK-47s, some [rocket-propelled grenades], hand grenades, ancient weapons in a modern age, for fighting against tanks and jets. We’re not asking for tanks and jets, but for ways to protect ourselves against tanks and jets,” said a former air force major general who would identify himself only as Abu George Al Golani for fear of reprisals against his family.

Golani, who now heads an 800-strong Free Syrian Army brigade in the countryside west of Damascus, said that the training offered by the United States in recent months consisted mostly of classroom exercises on how to treat prisoners of war, how to protect and report chemical weapons, and the basic use of light arms. “These are all things we know,” said Golani.

While the U.S. aid will for now be limited to light arms and ammunition, the Persian Gulf countries that have been providing the bulk of outside rebel supplies are prepared to begin immediately sending shoulder-launched surface-to-air missiles and to step up shipments of armor-piercing weapons. Until now, they have largely withheld such equipment at the request of the United States, according to U.S. and foreign officials who spoke on the condition of anonymity to discuss their decision-making.

Balance could shift

Arms deliveries, made through the rebels’ Supreme Military Council, could help shift the balance of power away from increasingly influential Islamist groups who already possess antitank weaponry, analysts say.

Participating governments have been working with U.S. officials on protocols to ensure that the weapons are distributed only to vetted rebel units and kept out of the hands of Islamic extremists fighting on the opposition side. Options under consideration include electronic tracking devices embedded in the weapons, videotaped distribution to individuals, and a requirement that launchers be returned before additional missiles are distributed.

The new weapons could help fend off creeping government gains. Bolstered by their capture of the town of Qusair near the Lebanese border this month, Syrian army troops have built up their presence in the countryside around the northern city of Aleppo and increased pressure on rebel strongholds near the capital, Damascus.

Rebels said the new weapons had already given them a boost. Ahmed al-Kateeb, a spokesman for Aleppo’s Northern Storm Brigade — whose leaders met with Sen. John McCain (R-Ariz.) during his brief visit to Syria last month — said the group had launched attacks overnight Thursday at several locations on the long, static front line between regime- and rebel-held areas of Aleppo after receiving a delivery including ammunition and Russian-designed wire-guided Konkurs antitank weapons.

“The situation in Aleppo is very hot,” he said.

Rebels had been waiting for weeks for the consignment, but it had been held up by the Turkish government, Kateeb said, adding that now that the United States has said it will provide arms, the rebels hope that delayed shipments from Libyan arms dealers will also arrive.

In an interview with al-Jazeera television Thursday evening, Gen. Salim Idriss, chief of staff of the rebel Supreme Military Council, thanked “brothers and friends” for sending new arms but called on the United States to “hurry” to send their own deliveries.

“We’re in a critical period when it may still be possible to re-energize moderate rebel forces back to preeminence amongst the wider opposition,” said Charles Lister, an analyst at IHS Jane’s Terrorism and Insurgency Center. “These latest arms shipments, if verified, are likely sparked by just such thinking.”

Videos filmed on the battlefield as far back as January show Konkurs antitank missiles being used by rebels, and have been posted with increasing frequency in recent weeks. The missiles appear to have been largely in the hands of Islamist groups, including Suqor al-Sham and Ahrar al-Sham, whose leader has expressed hostility toward the West.

“It seems, at least for now, that both moderates and more Islamist-orientated groups are receiving a boost from interested regional states,” Lister said, adding that if antiaircraft weaponry was included in deliveries, the impact would be “very significant.”

Hazem al-Shami, a spokesman for Ahrar al-Sham, said Thursday that small numbers of Konkurs antitank missiles in the group’s possession had been invaluable in repelling Syrian army advances north of Aleppo, where he says Assad’s forces are attempting to divide rebel-held areas in two. He said the group had not received new supplies of the antitank weapons.

Warning from Russia

Secretary of State John F. Kerry will lead the U.S. delegation to the Friends of Syria meeting in Doha, which will also include Britain, Italy, Germany, France, Egypt, Jordan, Qatar, Saudi Arabia, the United Arab Emirates and Turkey.

Britain and France, which are now technically free to arm rebel groups since a European arms embargo was allowed to lapse last month, have yet to announce whether they will do so. Russian President Vladimir Putin said Friday that the West should not send weapons to rebel forces that include “terrorists,” while defending the military support Moscow provides to the Syrian government.

“Where will [those weapons] end up? What role will they play?” he said at a Russian economic forum, according to Reuters news service.

Liz Sly and Ahmed Ramadan in Beirut; William Booth in Irbid, Jordan; and Karen DeYoung in Washington contributed to this report.