REYHANLI, Turkey — In the border towns where Syrian rebels recuperate and resupply, the buzz is that the long wait for Barack Obama may be near an end. The excitement is not the result of the White House announcement on June 13 that the United States will supply light weapons to the groups seeking to overthrow the homicidal regime of Bashar al-Assad. Bullets and body armor won’t help much against Assad’s tanks, bombs and mortars. But the rebels say they see Obama’s hand in some bigger, less-publicized developments: the arrival of more and better antitank weapons, and rumors of long-withheld antiaircraft weapons. The heavier ordnance is coming from Europe, the gulf and — as The Times reported Saturday — from Libya. But it seems to be flowing now with a wink and a nod from the U.S.

“These thing don’t happen without America’s permission,” said a logistics coordinator for a rebel unit fighting in Homs, the birthplace of the uprising.

When I set out to meet with Syrian rebel operatives in the wake of Obama’s halfhearted shift, I expected a reaction of rolled eyes, too-little-too-late and thanks-for-nothing. What I found was a surprising surge of optimism, a sense that something has changed — specifically, that America is inching toward more serious engagement.

Of course, nobody is saying this is yet a game-changer. Gen. Salim Idris, the former Syrian Army officer who heads the opposition Supreme Military Council, told me that while the Americans have become more helpful in recent days, the speculation about antiaircraft missiles is premature, and there is still no sign that the United States is willing to enforce a no-fly zone or use cruise missiles against Syrian airfields, which could shift the advantage to the rebels. (I’m told Qatar arranged a small shipment of surface-to-air missiles and the U.S. looked the other way.) Whatever the details, intentionally or not, Obama has raised expectations.