U.S. Suspends Nonlethal Aid to Syrian Rebels in North Medo Halab/Agence France-Presse - Getty Images A rebel fighter aimed his weapon during clashes with pro-government forces on Wednesday in Aleppo, Syria. WASHINGTON - The United States has suspended the delivery of nonlethal aid to the Syrian opposition in northern Syria after concluding that some of it has fallen into the hands of extremist Islamic fighters, American officials said on Wednesday. The decision was made after moderate Syrian rebel forces reporting to Gen. Salim Idris, the nominal head of the rebel Free Syrian Army, came under attack last week from fighters aligned with Al Qaeda, according to an account provided by an American official. The Islamic Front, an alliance of rebel fighters that has broken with General Idris's moderate opposition but opposes the Qaeda affiliate in Syria, joined the fray, the American official said. After the dust cleared, the Islamic Front appeared to have taken control of warehouses in Atmeh that contain equipment and supplies provided by the United States, added the American official, who spoke on the condition of anonymity because he was discussing internal reports. The first reports of military actions are often confused and inexact. But it seems clear that American officials are concerned that some aid has indeed fallen into the wrong hands. "We have seen reports that Islamic Front forces have seized the Atmeh headquarters and warehouses," a State Department official said. "As a result of this situation, the United States has suspended all further deliveries of nonlethal assistance into northern Syria," the official added. The humanitarian aid to the Syrian people is not impacted by this suspension. The episode illustrates two trends that pose major challenges for the Obama administration's goal of strengthening the moderate Syrian opposition and persuading President Bashar al-Assad of Syria to yield power. One is the growing strength of Qaeda-affiliated forces, including the Islamic State of Iraq and Syria. The other is the fracturing of the Assad opposition, which has led some commanders to break away from General Idris's Supreme Military Council, which the United States is backing, to form their own coalitions. Since suspending aid, American officials have begun an inventory to determine how much of the nonlethal equipment and supplies are controlled by forces reporting to General Idris. Under the Obama administration's division of labor, the State Department is in charge of supplying nonlethal aid, like radios, vehicles and food rations. The C.I.A. is running a covert program to arm and train Syrian rebels. "We are working with General Idris and the S.M.C. to inventory the status of U.S. equipment and supplies provided to the S.M.C.," the State Department official said, referring to the Supreme Military Council. We are gathering the facts and consulting with friends of the Syrian opposition on next steps in support of the Syrian people.