During more than three years of conflict, Syrian rebel groups have often been outgunned by the Syrian military. But opposition forces are apparently starting to get their hands on a different type of weapon.

What's most interesting, though, is where it comes from.

The BGM-71 TOW anti-tank missile system is made in America. It was first put into use by the US military back in the 1970s. On the battlefield in Syria's current civil war, though, it can give rebel fighters an edge against Syrian government forces.

Video footage, said to be from a relatively new faction of the Free Syrian Army called Harakat Hazm, shows men launching a US-made guided missile at what they describe as a government checkpoint. When experts noticed the video, along with some other recent footage of the American weapons, they took notice.

“It's a big deal,” says Andrew Tabler of the Washington Institute for Near East Policy. “It's not just that there are weapons going into Syria, it's that there are American-made weapons.”

Tabler says it doesn't necessarily mean the United States is supplying anti-tank missiles directly to Syrian rebels. US allies, Turkey and Saudi Arabia, both have supplies of these weapons. And it is probably safe to assume that one or both of these countries is providing them to the Syrian opposition, Tabler says.

Turkey and Saudi Arabia both want to see the end of the Assad regime, and they both have been providing arms to the Syrian opposition.

“We can also assume, to a large degree, that this is done with the knowledge of the American government,” Tabler says. “This would be in keeping with recent discussions about an uptick in support to the Syrian rebels.”

Administration officials are keeping quiet about the TOW missiles. But Frederic Hof of the Atlantic Council says the appearance of American anti-tank missiles in Syria seems to represent a shift in thinking for the Obama administration. Hof was US special envoy for Syria in 2012.

“It's a belated acknowledgment on the part of the United States that what's left of the nationalist armed opposition inside Syria really needs some assistance,” Hof says.

In other words, the so-called moderate opposition forces in Syria that the Obama adminstration says it supports now have their backs against the wall. And the White House might be trying to throw them a lifeline.

“It appears that the United States at long last is moving into a position of really influencing, if not directing, who gets what inside Syria in terms of arms and equipment for the armed opposition,” Hof says.

The Obama administration has been wary of providing weapons to Syrian rebels, fearing they might see US-supplied arms fall into the hands of extremist groups. Opposition forces in Syria are bitterly divided. At times, they have killed each other. Some rebel groups are linked with al-Qaeda.

Hof says the anti-tank missiles would have made a far greater impact had President Obama decided to deliver them a 18 months ago. "His key national security advisors recommended stepping up arming, training and equipping of [Syrian] nationalist rebels, because they were seeing at that time the beginnings of an al-Qaeda presence in Syria.”

“Better late than never,” Hof says.

But the two rebel groups thought to be in possession of the American-made BGM-71s are different, says Charles Lister of the Brookings Institution in Doha.

“Both of these organizations are comparatively new,” Lister says. But more importantly, he says both of them are "core Free Syrian Army, inherently moderate rebel organizations.”

It's thought that Syrian rebel forces now have about two dozen of the American-made guided missiles, which can be used against tanks, vehicles or buildings. Lister says the weapons could make a big difference in local battles. But he adds that they are not likely to turn the tide against Syrian government forces across the country.

“I'm skeptical that it will necessarily represent a game-changer,” he says. “Anti-aircraft weapons, in my view, would be the only weapon system that could potentially represent a game-changer.”

And even in the case of anti-aircraft systems, Lister says the rebels would require large numbers of them to tip the scales in their favor militarily.

No one seems to think Washington has anything like that in the works. Experts say the Obama administration might be looking at this first batch of anti-tank missiles as a test case. First, watch to see how they're used and who's using them. And then, think about what might come next.

Amr al-Azm is an associate professor at Shawnee State University and he's also a member of the Syrian opposition. He agrees that the appearance of US-made anti-tank weapons in Syria signals a shift in American policy. But he doubts that the Obama administration wants to help the rebels actually topple Bashar al-Assad's government.

"For the US, the dilemma has always been how to bring the Assad regime to serious negotiations without damaging it to the point where it collapses," Azm says. By most accounts, the current situation is not looking good for Syria's rebels.

"I think the US administration is essentially trying to shift things back to the stalemated position," Azm says.