– The defected Syrian general whom the United States has tapped as its conduit for aid to the rebels has acknowledged that his movement is badly fragmented and lacks the military skill to topple the government of President Bashar Assad.

Gen. Salim Idriss, who leads what's known as the Supreme Military Command, also admitted that he faces difficulty in creating a chain of command in Syria's highly localized rebellion, a shortcoming he blamed on the presence within the rebel movement of large numbers of civilians without military experience.

Idriss has become the key man in the international coalition that's battling to end the Assad regime. The United States announced in April that it would funnel $123 million in nonlethal aid through his group, an operation that's already begun. At the same time, U.S. allies, including Qatar and Saudi Arabia, agreed at a meeting in Istanbul that all lethal aid destined for the rebels would pass first to Idriss.

But whether Idriss and his Supreme Military Command can become a functioning military force remains a huge question. While U.S. Secretary of State John Kerry has said he was confident of Idriss' ability to deliver a coherent rebel strategy while keeping weapons away from Al-Qaida-associated Islamist groups, there's been little evidence that that's the case.

Shortly before Idriss was declared the conduit for all rebel assistance, Assad loyalists broke the siege of a key government base that rebels had been pressing for months. Fighters in that siege blame a lack of cooperation and ammunition for their failure, an assessment with which Idriss agrees.

"We don't have sufficient ammunition and weapons," Idriss said. "We don't have enough money for logistics, for fuel for the cars, for cars for the units. We can't pay salaries."

He acknowledged that he has little influence over what the rebels do in Syria and no direct authority over some of the largest factions, including the Farouq Brigade, whose forces control key parts of the countryside from Homs to the Turkish border.

In other developments:

• Kerry and Russian President Vladimir Putin said they'd convene an international conference later this month to try to corral Assad's regime and the rebels into talks on a political transition.

• Syrian rebels kidnapped four U.N. peacekeepers along the fraught cease-fire line between Israel and Syria in the Golan Heights, in a replay of a similar incident in March. The Yarmouk Martyrs Brigade announced that it seized the peacekeepers to "secure and protect" them.

The Associated Press and Washington Post contributed to this report.