Adding to the allegations of overt Western backing for the increasingly sectarian rebel fighters in the ongoing Syrian Civil War, Russian Gen. Nikolai Makarov said that his government has “reliable information” about rebel fighters having acquired US-made Stinger missiles, a shoulder-mounted anti-aircraft weapon.

“It should be cleared up who delivered them,” Makarov added. Pentagon chief Leon Panetta insisted he “certainly doesn’t know of us providing any such missiles in that area,” while the US State Department pressed for Russia to produce the evidence.

Past videos released by rebel fighters have shown them armed primarily with SA-7 anti-aircraft missiles, older Soviet-made weapons which were likely part of the massive stockpile looted at the end of the Libyan Civil War. Stinger missiles would be a considerable upgrade.

Of course weapons exported abroad have a way of finding themselves in the hands of third parties, as Swiss officials discovered over the past year, with Syrian rebels using Swiss-made hand grenades that were sold to the United Arab Emirates, then given to Jordan for “anti-terror” operations, then somehow wound up in Syrian rebel hands.

The US has been reluctant to provide anti-aircraft weapons to Syrian rebels for fear they would use them against civilian aircraft, which they have explicitly threatened to do. Yet the US has made tens of thousands of Stinger missiles over the years, and provided them to scores of countries and even a handful of rebel factions, so it is impossible for the US to say with certainty that such weapons aren’t going to crop up in rebel hands in Syria.