Samuel R. Berger is chairman of the Albright Stonebridge Group. He was national security adviser to President Bill Clinton from 1997 to 2001.

The Syrian regime’s unwillingness to seriously engage in Geneva makes clear that a parallel effort must be taken to shift the regime’s calculations and to allow the United States and the moderate opposition to return to negotiations in a better position. That is the only way this brutal war will stop.

Events in Homs illustrate the depravity of Syrian President Bashar al-Assad’s strategy of misery. But the conflict has taken on an ominous security dimension for the United States in recent months. Assad’s intensified assault, including his unrelenting bombardment of the more moderate elements of Syria’s opposition, has created a vacuum that is being filled by jihadist groups, who are also a threat to us. Director of National Intelligence James R. Clapper Jr. and CIA Director John Brennan told Congress last month that eastern Syria is becoming a haven for al-Qaeda and its affiliates — such as Jabhat al-Nusra and the Islamic State of Iraq and the Levant — and that some aspire to attack our homeland. Clapper testified that the Syrian insurgency has more than 7,000 foreign fighters. Many will return to their homes in Europe and elsewhere as trained, hardened combatants.

With no political solution immediately forthcoming, we need to shift course. The Geneva process should continue; it is how the war will end. But the United States must pursue a strong set of actions that would address the immediate threat posed by al-Qaeda in Syria and give Geneva a chance to succeed.

The United States will not be able to defeat al-Qaeda in Syria by itself. To counter it, we must strengthen the relatively moderate elements among the opposition. Only these groups, who speak and fight for the majority of the population and share the Syrian people’s desire to be rid of both Assad and foreign fighters, can seize and hold the ground claimed by jihadists. U.S. officials believe that the majority of fighters are not associated with al-Qaeda, though some are Islamists. Indeed, in recent weeks these forces have stood up against al-Qaeda in parts of Syria. If we don’t help them now, we could find ourselves responding to a terrorist attack originating from a new al-Qaeda enclave in eastern Syria — drawn in on its terms and timetable.

Fortunately, we can strengthen the moderate opposition in ways that would push back al-Qaeda’s gains and help change Assad’s equation. First, the United States needs to provide the moderate anti-Assad, anti-al-Qaeda forces the assistance they need to attract people away from the extremists — to build up liberated areas and counter regime attacks so they can focus on al-Qaeda. One of the best ways to do so may be delivering cash to pay salaries in liberated areas. By helping the opposition’s local government councils pay teachers, medical workers, civil servants and police officers, we can help them gain legitimacy and establish public order, creating a more viable alternative to the extremists and the Assad regime.

A similar approach could be pursued to bolster the brigades fighting al-Qaeda. Arms are also needed, but arms transfers are logistically complex and take a long time. Meanwhile, opposition fighters must feed themselves and their families. And extremist groups, flush with cash from their supporters in the Persian Gulf, pay more reliably and generously. It will be critical to vet opposition leaders and brigades receiving cash assistance while being realistic: Some may be diverted to bad actors. The alternative is that those bad actors would continue getting most of the assistance flowing into opposition areas, while the moderates get none.

Second, as the United States works to bolster the moderate opposition, the corollary is to limit the flow of arms to the Assad regime and extremist groups. The most effective method is to impose carefully targeted sanctions on banks that finance arms shipments to the regime and on financiers of al-Qaeda. Targeting these institutions would create obstacles to the regime’s resupply efforts and would place pressure on Assad’s international supporters to help us achieve a diplomatic resolution.

Finally, if we want to win the Syrian opposition’s full support against al-Qaeda, we must be willing to help it protect civilians from Assad’s atrocities, including the barrage of “barrel bombs” falling on opposition-held towns. Hindering Assad’s use of helicopters and jets to kill civilians would enable the moderate Syrian opposition to demonstrate that it has helped deliver some freedom from the constant fear of death from the air. It also would allow them to divert resources to fight extremists. There are many ways to achieve this goal with partners and allies, from working with proxies in the region to airstrikes — actions limited in scope and that do not involve U.S. troops on the ground.

When we look at Syria, we cannot simply see missed opportunities from three years of conflict. Core U.S. interests are at stake, and the status quo cannot continue. While there are risks to these steps, the alternative is far worse: al-Qaeda recovering from the blows the United States has dealt it and gaining a new stronghold, and Assad continuing his butchery. We must alter the circumstances to protect ourselves and to return to the negotiating table in a position to succeed.