It’s not enough to limit U.S. involvement in the war on Yemen. To pursue peace, Biden must also end military support for Riyadh. Give President Joe Biden some credit. He pulled the U.S. back from supporting Saudi Arabias six-plus year campaign of murder and mayhem against Yemen, one of the worlds poorest nations. The Obama and Trump administrations made Americans accomplices to Saudi aggression and war crimes. The Biden administration should end all military assistance in any form for Riyadh as long as the latter is involved in the conflict.

Modern Yemen has been convulsed by unrest and war for most of its six decades of existence. (Two states emerged in the 1960s and merged in 1990.) In the 2000s Ansar Allah, widely known as the Houthis, battled the government led by President Ali Abdullah Saleh, who was backed by the Kingdom of Saudi Arabia. In 2012 he was overthrown during the Arab Spring and replaced by his vice president, Abdrabbuh Mansur Hadi. Two years later Saleh and the Houthis joined to defenestrate Hadi, which prompted Saudi and Emirati military intervention.

This endless Yemeni infighting mattered not at all to the U.S.

Washington was most concerned about activities of Al Qaeda in the Arabian Peninsula (AQAP), long the most threatening affiliate of Osama bin Ladens old organization. However, the political game of musical chairs changed little. Saleh had cooperated with Washington against AQAP. The Shia (Zaydi) Houthis disliked America but hated the Sunni terrorist organization even more and demonstrated their antagonism on the battlefield.

Nor did Hadis ouster threaten the Kingdom, which had previously backed Saleh. The Houthis disliked the Saudi royals, who had intervened in Yemen to promote Wahhabisman intolerant variant of Sunni Islam that demonizes Christians, Jews, Shiites, and other non-Sunnis. (Riyadh also promoted the hateful theology throughout the rest of the world, including in American madrassahs.) Ansar Allah had contact with Iran, but the relationship was distant, not like the close ties between Hezbollah and Tehran. Indeed, Iran initially cautioned the insurgents against seizing Sanaa and confronting the Saudis.

However, Mohammed bin Salman, then defense minister on his way to becoming crown prince, apparently wanted a docile regime next door and intervened to back Hadi, who lost much of his popularity after calling in foreign airstrikes on his people. Under MbS the Kingdom became the Middle Easts most aggressive state, attacking Yemen, seizing Lebanons prime minister, underwriting civil war in both Libya and Syria, diplomatically isolating and militarily threatening Qatar, sustaining Bahrains autocratic Sunni monarchy, and more. At the same time, the crown prince launched a vicious political crackdown at home, highlighted by the gruesome murder and dismemberment of dissident journalist and American resident Jamal Khashoggi.

President Barack Obama was no fan of the antediluvian Saudisafter all, few people see absolute monarchy as the wave of the futurebut decided to back the corrupt, licentious royals in a vain attempt to win the Kingdoms acquiescence for the nuclear agreement with Iran. Alas, Riyadh never accepted Obamas reasonable belief that the Middle Easts most repressive state, a true totalitarian horror, ranked in the bottom ten worldwide by Freedom House, should share geopolitical space with Tehran. (Iran also is awful, but the Kingdom of Saudi Arabia is notably worse.) Rather, as former Defense Secretary Robert Gates observed, the Saudis expected to fight the Iranians to the last American. The royals took U.S. weapons and support as their due and continued to work to undermine the Joint Comprehensive Plan of Action.

Then Donald Trump was elected president, and he spent his entire term genuflecting to Riyadh, subcontracting Mideast policy to MbS. The Trump administration launched a manifestly counterproductive maximum pressure campaign against Iran, which left Tehran much closer to a nuclear weapon and the region much less stable. The Biden administration was left to confront the consequences.

Worst of all, Trump doubled down on backing Saudi aggression against Yemen. The U.S. supplied warplanes and munitions, serviced weapons, initially refueled Kingdom aircraft, aided targeting, and provided diplomatic cover. After MbS had Khashoggi sliced and diced at the Saudi consulate in Istanbul, Trump proudly announced that he saved [MbSs] ass. Observers marveled at the crown princes mysterious chokehold over the president.

The Saudi-led campaign created what the United Nations termed the worlds worst humanitarian disaster. The countrys infrastructure is wrecked. Tens of thousands of civilians are dead. Disease, malnutrition, and starvation afflict millions of the living. Roughly 80 percent of the population need aid to survive. Although Ansar Allah shares blame for what had become a national charnel house, the coalition dominated by the Kingdom and the United Arab Emirates caused most of the wars damage and deaths through its air attacks and naval blockade.

Candidate Biden campaigned against the murderous Saudi autocracy. After his inauguration he cited the unendurable devastation of the war and announced that he was ending all American support for offensive operations in the war in Yemen, including relevant arms sales.

However, the president engaged in a dubious form of moral equivalence, also expressing his determination to help Saudi Arabia defend itself against missile attacks, UAV strikes, and other threats from Iranian supplied forces in multiple countries. Similarly, the administrations special envoy for Yemen, Timothy Lenderking, complained that such strikes on targets in the Kingdom are not the actions of a group that claims it wants peace. The latter added that Biden and Blinken both made clear were not going to allow Saudi Arabia to be target practice.

There are few good guys in Yemens decades of turmoil. Certainly not Ansar Allah. Nor Hadi, Riyadh, Saleh, Iran, AQAP, UAE, or any of the other many combatants. Although most accounts of the war pit the Houthis against Hadi, both sides constitute multiple factions, many motivated more by who they hate than who they like. Indeed, the conflict has grown more complex over time. Robert Malley and Stephen Pomper of the International Crisis Group explained: The war now rages on multiple fronts, each with its own political dynamics and lines of command and control.

But if one action is entirely justified, it is Yemeni retaliation against the Kingdom. The Houthis first missile attacks and UAV strikes followed months of Saudi air attacks, supported by U.S. Unfortunately, the Saudis were most effective at bombing weddings and funerals, apartments and hospitals, and other civilian targetsand then denying responsibility. Even after withdrawal of American backing, the air war continues. The best way to encourage Ansar Allah to halt its assaults on the Kingdom would be for Riyadh to exit the conflict.

If the Kingdom wont quit, so be it. However, Washington should not be responsible for defending a country which knowingly engages in aggressive behavior that predictably results in retaliation. The royals should be held responsible for their actions. Instead, they appear to believe that being rich and pamperedand a client of Americaentitles them to visit death and destruction on others without consequence. Biden should not enable their vile behavior.

Similarly dubious is criticism of Iran for supplying Ansar Allah with weapons. Lenderking asserted that Tehran played a very negative role in Yemen. Bradley Bowman of the Foundation for the Defense of Democracies and Katherine Zimmerman of the American Enterprise Institute complained that Tehran has undertaken a major arms smuggling effort on behalf of the Yemeni insurgents.

Although these shipments are nothing compared to U.S. weapons sales to Saudi Arabia, Bowman and Zimmerman contend that ending U.S. supportfor brutal aggression and ongoing war crimes in a conflict of little interest or consequence for Americais putting tremendous pressure on Riyadh. So, the authors–ever solicitous of the tragic burden borne by the faltering royals–urge Biden to go all in on behalf of the aggressors: the U.S. Defense Department should position sufficient military resources in the region and provide commanders with clear instructions to prioritize the interdiction effort. The U.S. Congress should press the Biden administration on what it is currently doing to interdict Iranian weapons shipmentsand ask what more can be done.

The U.S. already has done enough harm by enabling the Saudis and (until recently) Emiratis criminal war in Yemen. Iran is a malign actor but trails far behind Saudi Arabia in culpability for the Yemen conflict. Tehran did not start the war. Rather, the murderous yet incompetent Saudi intervention provided Tehran with an obvious opportunity to bleed the royals. And, frankly, the U.S. which spent the last six years supporting the royals prosecution of this terrible conflict for political reasons, to support the Saudi dictatorshiphas no moral standing to criticize Iran for its much more modest supply efforts.

The Biden administration should set two objectives in Yemen. The first, and most important, is to end American complicity in the destruction of a nation and impoverishment of a people. The Trump administration turned the U.S. into an accomplice of one of the worlds criminal regimes. Biden reversed course and has halted support for Saudi offensive operations. Now he needs to refuse any military aid for the Kingdom as long as the latter is engaged in Yemen. Americans have no responsibility to protect an aggressor from suffering the natural consequences of its actions.

The second goal should be to encourage the end of the war in Yemen. The U.S. has little leverage with Ansar Allah, having spent the last six years acting as a de facto co-belligerent with the Kingdom. Indeed, Yemenis call the conflict the Saudi-American war. Yet State Department spokesman Ned Price told the Houthis to immediately stop these aggressive acts. Both sides should halt, but the State Department has no credibility. The Houthis are attempting to increase their bargaining power before talks, a common practice for combatants throughout history. Washingtons sanctimonious criticisms arent likely to influence the movements behavior.

Better for Washington to press the other Gulf States to present a positive vision for the benefits that could follow a negotiated peace. Even more important, the U.S. should move on the JCPOA and develop a better relationship with Iran. If Washington wants Tehran to respond with less belligerence, then America must do the same. Ringing Iran with forces and bases, threatening military action, and attempting to starve the population could not help but put any regime, and especially one like the Islamic Republic, in a paranoid and hostile state. If the U.S. wants Tehran to reduce support for the Houthis, then Washington should change its own behavior as well.

Yemen is a terrible war. A political solution is necessary. Thankfully, the Biden administration has limited U.S. involvement. However, after spending six years helping Saudi Arabia kill Yemeni civilians, Washingtons attempt to play peacemaker is likely to be met with understandable skepticism. To help end the conflict that America did so much to stoke, the administration should end military support for Riyadh and more seriously engage Tehran. Otherwise, the war is likely to continue to burn, destroying even more of Yemens land and people.

Doug Bandow is a senior fellow at the Cato Institute. A former special assistant to President Ronald Reagan, he is author of Foreign Follies: Americas New Global Empire.