Sudan’s prime minister announced last weekend that Sudan began drawing down its forces in Yemen, saying “there is no military solution” to the conflict. This marks another step in the Saudi-led coalition’s de facto drawdown, after the United Arab Emirates (UAE) announced its own withdrawal over the summer and Saudi Arabia began engaging in Oman-led peace talks with the Houthis this fall.

What does the intervening coalition’s slow but steady drawdown mean for Yemen’s civil war? While there is still a long way to go to reach a lasting peace in Yemen, this moment probably marks the beginning of the end of the war — or at least this phase of the war. Whether the civil war in Yemen ends for good will depend in part on the role of external actors.

Ending the civil war in Yemen

The current war in Yemen has deep roots in regional dynamics and historical grievances among local groups. As a result, fighting among local armed groups will not necessarily end even after the Saudi-led coalition withdraws. Although regional actors have exploited the conflict in their own competition for influence, the war began over local grievances around governance and resource-sharing. Much about whether and how the war ends will depend on the decisions of these local Yemeni actors themselves, and whether they are included in an agreement. Nevertheless, the impending end of the intervention marks a turning point in a war that has killed more than 100,000 people and created the world’s worst humanitarian crisis.

Countries in the region will play a critical role in ensuring that the war ends in a durable settlement — or resumes in a new iteration following the coalition’s departure. They can help end civil wars by overseeing a country’s commitment to resolving conflict and preventing the emergence of spoilers, or actors that actively seek to disrupt conflict resolution processes. My research with Lise Howard has found that civil wars tend to end the way that external actors think they ought to. Civil wars are also more likely to resume following negotiated settlements than after victory by one side to the conflict or a cease-fire. In negotiated settlements, if one side lays down their weapons, they have no guarantee that the other side will not take advantage of this imbalance to continue the fight.

Oman played an important role as a third-party broker, and Saudi Arabia and the UAE were willing to pressure their partner forces to end the recent power struggle in the south of Yemen. As external mediators and guarantors, they can help political leaders and armed factions in Yemen come to an agreement and prevent the emergence of spoilers who try to undermine it.

Once an agreement has been struck, external groups can deter armed factions from resuming the fight by raising the costs of noncompliance. My own research has found that regional actors are more likely to restrain their intervention when a great power partner uses leverage, such as threatening to cut economic aid or arms sales, to persuade them to do so. The United States has an especially important role to play here. By keeping up the pressure on its security partners Saudi Arabia and the UAE, the United States can help prevent the resumption of the intervention and place indirect pressure on local actors who receive Saudi and Emirati support to stick to the terms of an agreement.

Why this time is different

The idea that the Yemen civil war could end following the coalition’s drawdown may at first glance read as overly optimistic. Cease-fires and peace negotiations in Yemen have faltered plenty of times in recent years. Most recently, southern factions failed to reach a power-sharing agreement before the Dec. 5 deadline, even at the urging of their Saudi and Emirati backers.

Current circumstances point to reasons for cautious optimism. The Trump administration has subtly changed its messaging on the conflict in recent days. Previously, administration officials had painted the Houthis as Iranian proxies and Yemen as an arena for regional conflict with Iran, thus justifying the coalition intervention.

Last week, however, State Department Iran envoy Brian Hook sought to draw a line between the Houthis and Iran, stating that “Iran clearly does not speak for the Houthis” and implying that the Houthis are playing a constructive role in peace talks.

The rhetorical shift implies that U.S. officials may be genuinely interested in ending the conflict rather than continuing to support the coalition as part of a broader “maximum pressure” strategy on Iran.

Another obstacle to a lasting settlement may be Saudi Arabia and the UAE’s diverging interests in Yemen: Saudi Arabia is primarily concerned with dislodging the Houthis and reducing Iranian influence, while Emirati leaders want to prevent the influence of Muslim Brotherhood-affiliated parties and expand their commercial empire and military presence along the Red Sea coast. However, both countries receive billions of dollars in arms sales and training from the United States, giving the United States considerable leverage. This leverage can help get these regional partners on board.

What makes peace agreements last?

Peace agreements are more likely to last when they include women and civil society actors at the negotiating table. Inclusive negotiations are better able to reflect and account for a broader range of concerns. In 2011, a regional initiative brokered Yemen’s National Dialogue Conference (NDC), meant to lead to new elections after Yemen’s Arab Spring movement. While the NDC required that a certain proportion of delegates be women, southerners or young people, the process failed in part because it lacked true grass-roots participation and buy-in. This time, the international community has the opportunity to play a more constructive role in encouraging a genuinely inclusive peace process.

Security sector reform also contributes to the durability of peace agreements. There is a multitude of local security groups that will need to be reconciled to and integrated within the state that emerges from a peace process. It would also be a chance to help resolve underlying conflicts among local groups. For example, former southern military and government leaders ignited the southern secessionist movement in Yemen after they were excluded from the post-1990 unification government. International aid can support security sector reform programming to demobilize and reintegrate armed nonstate actors, provide security for civilians, and establish civilian oversight over armed forces to help prevent continued conflict.

Much will depend on the decisions of local Yemeni actors themselves. But by resolving commitment problems and supporting (or failing to support) initiatives that make settlements more durable, external actors have played, and can continue to play, a critical role in ensuring that the Yemeni civil war ends — and stays ended.

Alexandra Stark (@alexmstark) is a senior researcher at New America.