The Pentagon is reportedly considering ramping up US support for Saudi Arabia’s bloody war in Yemen, which has already killed at least 10,000, displaced 3 million, and left millions more at risk of famine since it began in March 2015.

That would be a major shift from the current US mission there, which has largely focused on using drones and special operations forces to batter al-Qaeda’s affiliate in Yemen. (US Navy SEAL William “Ryan” Owens was killed during one such raid in January.) Under the potential new plan, the US would be intervening much more heavily in a bloody and so far intractable civil war — potentially leaving Washington ensnared there for years to come.

The fight in Yemen pits the Saudi-led coalition — which also includes aircraft from the United Arab Emirates and other Gulf countries — against Houthi rebels backed by Iran. The Houthis ousted the US- and Saudi-backed Yemeni government of Abd Rabbu Mansour Hadi. Saudi Arabia, which sees Houthis as proxies of Iran, its biggest regional rival, responded with a military campaign aimed at ejecting the Houthis and returning Hadi to power.

Since the war began, the US has been giving direct military support to the Saudi campaign, including providing aerial refueling of the Saudi warplanes that have hit schools, hospitals, and other civilian targets across the country.

That’s already raised serious questions about whether the US is complicit in potential Saudi war crimes. Should the Trump administration decide to increase the Obama administration’s initial support for the Saudi war effort, the already dire situation in Yemen will likely get even worse. And at least some of the responsibility for the carnage will lie, rightly, at Washington’s feet.

So why, exactly, is the US supporting this war? In a word, Iran.

The Saudis — longtime US allies — were less than thrilled when the Obama administration inked its landmark nuclear deal with Iran, believing it would only embolden Tehran’s regional ambitions.

The nuclear deal explicitly did nothing to address Iran’s support for armed groups in the region — including the Houthis — and eased a number of nuclear-related sanctions on Iran. The Saudis (and many others) feared that as a result, Iran would be able to spend even more money in support of those armed groups, which it uses to spread its influence in the region.

To help assuage Saudi fears and counter Iranian influence, the Obama administration essentially agreed to assist Saudi Arabia in its war against the Houthis in Yemen. This, it seems, continues to be the rationale for why the Pentagon is now considering increasing US support for the Saudi-led war.

“The Pentagon views increased support for the Saudi-led coalition as one way of potentially pushing back against Iran’s influence in Yemen,” report Foreign Policy’s Dan De Luce and Paul McLeary, “as well as shoring up ties with an ally that felt neglected by the previous administration.”

The Washington Post reports that Defense Secretary James Mattis has “asked for removal of President Barack Obama’s prohibitions, which would enable the military to support Emirati operations against the Houthis with surveillance and intelligence, refueling, and operational planning assistance without asking for case-by-case White House approval.”

Trump has long talked tough on Iran. During the campaign, he frequently criticized the nuclear deal, and his running mate Mike Pence promised, “when Donald Trump becomes president of the United States of America, we’re going to rip up the Iran deal!” And back in February, the Trump administration announced it was putting Iran “on notice” in the wake of the Islamic Republic’s latest ballistic missile test.

So far, though, Trump has not taken any steps to get rid of the Iran deal, and in fact seems to be signaling that he will continue to uphold the pact. Upping US support for the Saudi war on Yemen, then, is one way for the Trump administration to look like it’s getting tough on Iran without having to dismantle the Iran nuclear deal.

The war in Yemen has been a disaster

The war in Yemen has not exactly gone as planned. The Saudi-led coalition has killed large numbers of Houthi fighters but has also suffered significant civilian casualties of its own. After two years of brutal fighting, the Houthis are still in control of much of the country, including the capital, Sana'a. The fighting shows no signs of stopping.

Neither, unfortunately, does the rising human cost of the war. According to the United Nations and other outside monitors, the fighting has killed 10,000 and left 370,000 children malnourished and 10,000 more dead of preventable disease. Nearly 3 million Yemenis have been pushed out of their homes.

The Obama administration condemned the civilian death toll in Yemen and urged the Saudis to exercise more restraint, at one point even halting some arms sales to Riyadh. Still, there is no question that American support — the US had flown more than 1,600 refueling missions, or roughly two a day, as of late November 2016 — has made it easier for Saudi Arabia to bomb Yemen, and has directly contributed to Yemen’s immense suffering.

The increased US military aid would reportedly include “intelligence sharing, equipment, and training” for Saudi pilots and troops. That could theoretically help diminish the scale of the suffering by helping the Saudis more accurately target Houthi military installations instead of civilian targets like schools and hospitals, and by leveraging US assistance in order to force the Saudis to adhere to international laws of war that prohibit such targeting.

But observers and officials in Washington (and in the UK, which is also heavily involved in supporting the Saudi war effort) have been making that same argument for the past two years, and the Saudis are still targeting civilians with abandon. Should the Trump administration decide to increase US military involvement in the war, the plight of the millions of Yemenis trapped in the region’s poorest country is likely to get worse, not better.

Even if the Trump administration doesn’t decide to go that route, it could still inflict serious harm on the country by dramatically ramping up drone strikes there, which often result in civilian casualties. On top of that, the administration has tried twice to impose a travel ban on all Yemenis coming to the US, essentially attempting to block people fleeing a US-backed war from coming to the US for refuge. (In a rare instance of agreement, the US-backed Yemeni government and the Houthi rebels have both condemned the travel ban.)

Finally, the Trump administration’s proposed budget calls for drastic cuts in funding to the State Department, the United Nations, and USAID. While it is not clear whether Trump intends to cut humanitarian aid to Yemen specifically, any reduction in funding to aid organizations involved in Yemen is likely to further exacerbate an already dire situation.

Watch: The US may be aiding war crimes in Yemen