The battle for eastern Aleppo, Syria’s largest city, is not even over yet but forces backing Syrian President Bashar al-Assad already have their sights on their next target; the nation’s capital, Damascus.

Russia has ramped up its airstrikes and regime forces have more aggressively attacked rebel-held areas around Damascus, taking several villages and suburbs in the last week alone.

And yet, the growing regime grip around the capital has gone largely unnoticed as the focus has been on eastern Aleppo’s apparent imminent collapse. The regime is therefore poised to take new territory around Damascus regardless of whether its forces can seize and hold the rest of Aleppo city. If the regime can hold onto Aleppo, it would control nearly every major provincial capital in the country—Damascus, Homs, Hama and Latakia—and would be able to devote all its resources to taking the rural and suburbans towns around them, which opposition forces are in greater concentration.

The more the regime can claim under its control, the less influence the U.S. and its backed forces will have on the outcome of the war.

The fall of areas like eastern Damascus “removes American options for meaningfully challenging the regime through proxy forces,” Jennifer Cafarella, a Syria analyst for the Washington-based Institute for the Study of War, told The Daily Beast

Indeed, among some U.S. officials there was a sense of frustration Monday at the increasing collapse of U.S.-backed Free Syrian Army rebels in eastern Aleppo and the unwillingness of the U.S. to respond. That was not likely to change, officials said, as the Obama administration enters its final weeks.

The regime’s sweep of areas around Damascus this week has been swift and aggressive.

In the last two days, the regime reclaimed control of the city of al-Tall, north of Damascus, shortly after reaching an evacuation agreement.

On Monday, according to the Syrian Observatory for Human Rights, 1,400 civilians and 1,450 rebels boarded 42 government buses and another 25 ambulances filled with injured residents and left the Damascus suburb of Khan al-Shih, the only opposition held area on a key route southwest of the capital. The residents left as part of an evacuation deal negotiated by the government a day earlier, allowing residents to flee to other opposition-held areas.

And in Ghouta, a city east of Damascus (the eastern part of which the regime hit with a sarin gas attack in 2013), the Syrian Army has made advances as Russian forces have ramped up airstrikes.

“In the past three weeks, we’ve experienced new waves of strikes coming from the sky and the ground. These strikes have been hitting residential areas, particularly schools. There are still functioning medical centers but we are barely coping with this new wave of violence,” a doctor working at a makeshift clinic in eastern Ghouta told Doctors without Borders Friday.

The regime push into eastern Aleppo over the weekend has inflicted the biggest losses for opposition forces since Free Syrian Army took control in 2012.

The regime has leaned heavily on outside help from Iran and Russia in its recent push into eastern Aleppo. Iran has sent in so many reinforcements in Aleppo that it hasn’t required the deployment of as many Syrian forces, allowing the regime to expand toward reclaiming areas around the capital, observers said. Should Aleppo fall, Iranian forces could move toward the capital.

Roughly a third of eastern Aleppo fell out of opposition hands, largely in the north, in the past day, delivering a loss that was both psychological and tactical. Eastern Aleppo has been the cornerstone of the opposition, which has fought against Russian airstrikes, water and food shortages for months. Part of the help for the U.S.-backed opposition has come from al Qaeda, the most effective anti-Assad force on the ground.

According to the Syrian Observatory for Human Rights, roughly 10,000 civilians have fled the regime captured parts of eastern Aleppo in recent days. Officials have estimated that as many as 250,000 civilians remain in opposition controlled Aleppo.

Even if the regime has begun looking past Aleppo, the fate of the city likely will change the trajectory of the war. ISW’s Cafarella said that, if Aleppo does indeed fall, the opposition and jihadists could retaliate by targeting Alawite populations along the coast in places like Latakia. And it is that targeting that would force the regime to recalculate its focus on areas around Damascus.

Moreover, a regime victory in Aleppo would eliminate the elements of the opposition that had been willing to work with the U.S. to limit al Qaeda influence in Syria. That is, Aleppo’s fall would all but end U.S. influence a key part of the war, northern Syria.

“It is hard to see how U.S.-backed groups recover from the loss of Aleppo,” Cafarella explained. “And it will ensure that Turkey and Qatar are the only countries with real influence within the opposition.”