Saudi Prince Mohammed bin Salman and President Trump last year

The Saudi intervention in Yemen is a strategic catastrophe that has added to regional chaos and fostered the most acute humanitarian crisis on the globe.

During Saudi Crown Prince Mohammed bin Salman‘s visit to Britain, Prime Minister Theresa May was to “raise concerns” about the humanitarian situation in Yemen. “She will acknowledge the steps taken recently by Saudi Arabia to address the crisis,” May’s office said before the visit, “but stress the importance of full and unfettered humanitarian and commercial access, including through the ports.”

This may be better than nothing but May and President Trump, now that bin Salman is in America for his two-week long visit, must do more than “raise concerns.” They must stop making the Saudi intervention possible. The U.S. gains nothing from taking sides in a Mideast civil war.

It is no exaggeration to say the coalition campaign would not happen—at least, not anywhere near its present scale—without Western backing. As Sen. Rand Paul explained at a hearing on the subject last year, the United States is “supplying the Saudis with bombs, refueling the planes, picking the targets.” In addition to the weapons sales, refueling, and intelligence support Paul listed, Washington further enables Riyadh’s war by using the U.S. Navy to enforce the Saudi blockade which is quite literally starving the Yemeni populace.

The reasons for severing American and British support for the Saudi-led coalition are many. From a strategic standpoint, involvement here drags the United States deeper into the regional Sunni-Shiite power struggle, a theo-political battle Washington cannot (and shouldn’t attempt to) solve with U.S. military might. Furthermore, while it might be in Saudi Arabia’s interests to contain the violence of civil war in a neighboring country—though, to be clear, the coalition’s actions have not contributed to Yemeni stability—the United States has no comparable interests at stake, let alone of a vital nature. Washington’s role cannot be labeled defense.

The wisdom of subsidizing the Saudis becomes even more dubious when we consider the intervention’s side effects for terrorism.

While the coalition fights the Iran-backed Houthi rebels, who seek to overthrow Yemen’s internationally recognized government, the local branch of al Qaeda has flourished. Al Qaeda in the Arabian Peninsula (AQAP) is considered the organization’s deadliest faction, and it has made ample use of the chaos and anger the Saudi coalition’s airstrikes and blockade have engendered.

“As the coalition campaign began, AQAP increased its numbers and war chest by staging a massive jailbreak, seizing military hardware and robbing the central bank,” explains Elisabeth Kendall, a senior research fellow in Arabic at Oxford’s Pembroke College, notes in a commentary for The Washington Post. Taking what Kendall described as a “gradualist approach to governance,” AQAP has increased its influence by working with tribal leaders in Yemen, ingratiating itself with the population by focusing on basics like utilities over extremism. The result? “As coalition bombs rained down in Yemen’s west, crippled by the Saudi naval blockade, AQAP’s territory looked like a haven of stability.”

AQAP has grown wealthy because of the blockade, too, because it is willing to coordinate imports legitimate businesses cannot. And it has grown popular because of the U.S.-Saudi airstrikes, which serve as a constant source of anti-American messaging. “You think that Yemenis don’t know where the bombs are coming from?” Paul asked incredulously at the hearing last year. They do know, because AQAP tells them, feeding off the U.S.-facilitated Saudi war to fill its coffers, spread its false narrative, and expand its power. That growth means supporting Riyadh not only fails to defend the United States but actually makes us less secure, for while the chaos of the Yemeni civil war is far from U.S. shores, AQAP’s explicit aim is to perpetrate terrorist attacks on American soil.

Then there’s the humanitarian toll. Yemenis have suffered mass displacement, and the Saudi blockade has created a man-made famine. Nearly two million Yemeni children under the age of five are severely malnourished. Though Riyadh claims the blockade’s sole purpose is keeping Iranian weapons out of Houthi hands, in practice, it means the medicine and food imports on which Yemen relies are increasingly impossible to obtain. Clean water is scarce, so a cholera epidemic is sweeping the country. More than one million cholera cases have been diagnosed already, a staggering number in a country of 27 million. The desperation of Yemeni civilians’ condition is at this point difficult to overstate, and Saudi Arabia’s slight relaxation of the blockade in December was a half measure at best.

While the House of Representatives voted to declare U.S. intervention in Yemen unauthorized by Congress (as the Constitution requires), the resolution was nonbinding and has had no apparent effect on U.S. policy. Potentially more potent is a joint effort from Sens. Mike Lee (a Republican), Chris Murphy (a Democrat), and Bernie Sanders (the independent from Vermont) to demand a binding vote. “We believe that since Congress has not authorized military force for this conflict, the United States should play no role in it beyond providing desperately needed humanitarian aid,” they wrote in a February op-ed. “That is why we are introducing a joint resolution that would force Congress to vote on the U.S. war in Yemen. If Congress does not authorize the war, our resolution would require U.S. involvement in Yemen to end.”

The senators are right in their elucidation of Congress’ constitutional war powers. Washington must recognize its support for the Saudi coalition is a counterproductive “government failure,” as the senators wrote, and it would be wise to change course. While May is busy raising concerns, Congress may finally act.

Bonnie Kristian, a weekend editor at The Week, is a fellow at Defense Priorities. Her writing has also appeared at Time Magazine, CNN, Politico, USA Today, Relevant Magazine, The Hill, and The American Conservative.