RIYADH, Saudi Arabia — Crown Prince Mohammed Bin Salman, who arrives in Washington this week, is a man on a mission with a story to tell. It’s an appealing if slightly embellished narrative: about his economic vision, desire to promote a more moderate form of Islam, recognition of women’s rights and empowerment of a younger generation. But it’s a narrative that should not silence the other, far less rosy story of Saudi Arabia’s military intervention in Yemen. As it trudges toward its third-year anniversary this month, Riyadh’s campaign in its destitute neighbor’s civil war has been an unmitigated disaster.

The tragedy is threefold: the humanitarian consequences of the war have been dramatic; it has significantly worsened the situation that Saudi Arabia’s involvement was intended to address; and — unlike other ruinous ongoing Mideast conflicts — a realistic negotiated solution could be within reach. The war has been medieval in its brutality. More than 8 million Yemenis are on the verge of starvation out of a total 22.2 million in need of humanitarian assistance — figures roughly the equivalent, respectively, of the entire populations of Virginia and Florida. With more than 1 million suspected cases, the country has witnessed the worst cholera outbreak in modern history. Only half of Yemen’s health facilities remain functional, and even those lack the necessary medicines, equipment and staff. Casualties, inevitably underreported under these conditions, have been estimated at more than 10,000 civilians dead — a figure first announced by the United Nations in January 2017. The head of the U.N. office for the coordination of humanitarian affairs has called the situation an “apocalypse,” warning that if things do not change, “we are going to have the world’s worst humanitarian disaster in 50 years.”

Saudi Arabia is far from alone in bearing responsibility. But its repeated obstruction of humanitarian aid and commercial shipments, closure of Sanaa’s international airport and bombing of civilian targets — including homes, markets, schools and critical infrastructure — have played a considerable part.

Nor has the war brought Riyadh closer to its self-proclaimed objectives. Saudi Arabia is less secure today than it was three years ago. The Houthi rebels it is fighting launch almost daily incursions into Saudi territory. They have greatly improved their missile technology — in no small part thanks to Iran — and fire rockets deep into their northern neighbor. Two have reached Riyadh. While the Saudis purportedly entered the war to roll back Iranian expansion, their intervention is producing the opposite, tightening the Houthi/Iranian alliance while handing Tehran a low-cost means of keeping their rival bogged down in a country Iran doesn’t care much about.

As is customary for officials from virtually all countries involved in military operations of this sort — the United States included —  Saudis will say it is just a matter of time. They point to Houthi losses and their own allies’ gains. This year, they recently told us in Riyadh, will be the critical one — just as they said 2015, 2016 and 2017 would be. Yet Crisis Group’s field work in Yemen makes a few things clear: Yes, the Houthis are unpopular even in their northern strongholds, but they are a tough, indigenous force with a knack for tribal politics and guerrilla warfare. The war has left them better resourced, financially and militarily, than ever before. The Saudi-led coalition’s intensive bombardment inspires deep resentment in the north, giving the Houthis nationalist cover for their actions. They are not about to surrender.

Even if the Saudi-led coalition (the largest other participant is the United Arab Emirates) advances along the Red Sea coast, as it appears to be doing, the Houthi front will not collapse. The most the Saudis can hope for is prolonged guerrilla warfare in the inhospitable northern highlands. This best-case military scenario would continue to bleed Saudi Arabia financially, erode its international standing and intensify hostility toward both the kingdom and its U.S. ally in these areas, all the while deepening Yemeni misery.

Making the situation simultaneously more heartbreaking and more hopeful is that Riyadh possesses keys to a realistic solution that would promote its interests. In conversations with Crisis Group analysts, in person and through social media, Houthis have stated they want to negotiate with Riyadh. This could be because they feel emboldened after they killed their erstwhile ally, former Yemeni president Ali Abdullah Saleh, and no longer need worry that he might strike a deal behind their backs. It could be, as their enemies suggest, because they are weaker in the wake of an assassination that rallied opposition to them and want an agreement while they are still ahead. No matter — their desire for talks is an opening.

This presents an opportunity for Mohammed bin Salman. First, the crown prince could unconditionally allow unhindered humanitarian and commercial access to all Yemeni ports. After imposing a full blockade in November 2017 in response to a Houthi missile fired at Riyadh, Saudi Arabia has eased restrictions, allowing a partial opening of the Houthi-controlled Hodeida port, subject to 30-day renewals. But more can be done to address delays and ensure a permanent opening. This would be the right thing to relieve civilian suffering while also clearly putting the onus on the Houthis to facilitate humanitarian access to areas they control. He should also allow the resumption of limited commercial flights to Sanaa airport, giving civilians living in Houthi-controlled areas a lifeline to the outside world. Saudi Arabia’s legitimate security concerns could be addressed by enhancing the existing U.N. inspection mechanism for commercial goods entering Houthi-controlled ports and by ensuring security checks of commercial flights to and from Sanaa in Saudi Arabia or another designated country.

Next, his representatives can engage with the Houthis to devise a set of principles that would allow Saudi Arabia to end the coalition’s military intervention and support inclusive intra-Yemeni negotiations led by the new U.N. envoy. The Houthis would need to sever military ties to Tehran, secure the border, halt missile strikes and gradually hand over heavy weapons — notably missiles — to a new Yemeni coalition government of which they would form a part.  In return, Riyadh could accept a gradual demobilization of all nonstate militias (Houthis but also Riyadh’s local allies) and agree that the Houthis will enjoy a significant stake in the country’s government and military.

Such a deal may not end the violence. Three years of fighting have aggravated the country’s regional and confessional divides, fed local struggles and empowered an array of militias. The country is fragmented and may even divide permanently into separate states. At minimum, however, a deal would give Yemenis the space to seek a negotiated local settlement. The risk of a Houthi missile striking Riyadh or disrupting Red Sea shipping, and potentially provoking a wider regional confrontation, would recede. A pivot from war to politics would allow Iran far less maneuvering room and would provide opportunities to undermine Houthi hard-liners within the movement while empowering those animated by more pragmatic local aims. It would provide Riyadh an exit ramp from a war that has harmed its security, its international reputation and, increasingly, its standing in Washington.

President Trump could play an important role, if he’s willing to do so. He should use his meeting with the Saudi crown prince to make clear that continued U.S. support for the coalition will be unsustainable unless Saudi Arabia halts its attacks on civilians and civilian objects, stops hindering the shipment of humanitarian assistance and other commercial goods into Yemen, and moves forward with a peace initiative along these lines.

In response to such suggestions, Saudis regularly complain that they did not begin this conflict, Iran is aggravating regional tensions, Tehran is aiding the Houthis, Houthis are at least equally responsible and the horrors in Syria are far worse. All of which may be true, but most of which is beside the point. The United States is sanctioning Iran, providing Saudi Arabia with billions’ worth of weapons and directly assisting its coalition’s operations in Yemen. Saudi Arabia is a U.S. ally and far from an inconsequential one at that. An alliance must go both ways. When it comes to U.S. interests and the fate of the Yemeni people, the direction Riyadh has taken in Yemen simply is not the way to go.