Jet fighters of the Saudi Royal air force. The U.S. are struggling with their ally's airstrikes in the region | FAYEZ NURELDINE/AFP/Getty White House divided over Saudi airstrikes As civilian casualties mount in Yemen, some worry the U.S. is abetting war crimes.

Saudi Arabia’s airstrikes in Yemen, conducted with U.S. assistance, are alleged to have killed at least 1,500 civilians, dividing members of the Obama administration over whether the U.S. risks being accused of abetting war crimes in a bombing campaign that could ultimately strengthen Islamist militants.

Sources inside the administration say they are struggling to keep in check the opposing sides in Yemen, one of the clearest examples of the intensifying Saudi-Iran proxy war in the Middle East. But even as reports of civilian suffering and terrorist gains pile up, U.S. officials believe that reducing American support for the Saudis could make the situation even worse.

The White House does not want to anger Saudi Arabia, a vital, oil-rich ally already unhappy with President Barack Obama’s decision to pursue a nuclear deal with Iran. At the same time, what many hoped would be a short Saudi-led campaign against the Iran-backed Houthi rebels who overthrew Yemen’s government, is now entering its eighth month with no end in sight.

“The White House is increasingly frustrated with the Saudis, and they’re trying to figure out how to handle it,” said one foreign policy expert familiar with the administration’s deliberations. Private conversations seem to be having limited effect, the source said, but "the U.S. is walking on such eggshells around Saudi when it comes to the public domain that they’re not willing to ramp up their public pressure."

That hesitation appears to be deepening internal rifts in the administration. A former U.S. official said the divisions are between administration members who fear “this humanitarian toll is ultimately going to be a stain on our reputation and we’re going to end up holding the blame as well as anyone else" and others who "will say it’s very important to restore order and deliver a very clear message about the intolerance that we as a nation and community of nations will have for this type of seizure of power."

A State Department official acknowledged that different U.S. government factions have different opinions on how best to work with the Saudis to reduce civilian deaths, but he insisted that there's broad consensus that the conflict in Yemen needs a political solution, and soon. He noted that the parties involved recently agreed to enter peace talks, although past attempts at reconciliation have collapsed.

When asked if the U.S. was frustrated with the Saudis, the official chuckled and said, "We're always frustrated with everyone."

Saudi Arabia began airstrikes in Yemen in late March after the Houthis had made significant advances and forced Yemeni leader Abd Rabbu Mansur Hadi to flee the capital, Sanaa. The U.S. was given little notice, but the Obama administration quickly aligned itself with the Saudi monarchy, offering what it describes as logistical and intelligence support. The Saudi military campaign, which also has a ground element, began as the administration was trying to ease Saudi concerns about the nuclear deal with Iran, which Riyadh fears will embolden its top regional rival. It also came in the wake of power shifts in Saudi Arabia.

The prospect of Shiite-majority Iran calling shots in neighboring Yemen, a rugged, impoverished country of 24 million, was a red line for the Saudis, who follow a strict form of Sunni Islam. The Saudi-led coalition fighting in Yemen also includes Qatar, the United Arab Emirates and other states wary of Iran's rising influence.

Still, Iran's role may be more limited than advertised by the Saudis, and sectarianism is only one element of the fight. The Houthis, while Shiite Muslim, also have been aided by forces loyal to Ali Abdullah Saleh, the former Yemeni president who lost power in the wake of the Arab Spring and was replaced by Hadi.

What appears certain is that "the Saudis are in this for the long haul," said Fahad Nazer, a former policy analyst at the Saudi embassy in Washington, D.C. "They continue to be very resolute in this campaign."

The Saudi-led coalition has made significant gains against the rebels since March, but that has been coupled with tremendous civilian suffering. Around 2.3 million people have been displaced, and food, water and fuel are running short, human rights groups say. An estimated 2,500 civilians have been killed in the conflict, roughly two-thirds allegedly due to strikes by Saudi Arabia and its allies. The distribution of humanitarian and commercial goods has been hampered by the fighting as well as blocked ports and slow inspections of cargo ships, aid groups allege. In an Oct. 19 letter to members of the U.N. Security Council, the groups also noted that the Saudi airstrikes often hit schools and hospitals.

Similar concerns have been raised in Congress, where Democrats in particular are wondering whether the Saudis (and by implication the Obama administration) have an endgame. Sen. Patrick Leahy (D-Vt.), reportedly questioned whether the Obama administration is violating a law he authored that limits U.S. assistance to foreign armies that commit human rights abuses.

On Thursday, Sen. Chris Murphy (D-Conn.) aired concerns about U.S. military sales to the Saudis and said Congress needs to probe "whether the United States’ current participation in this [Yemeni] civil war is advancing our nation's national security interests." In the House, 13 congressmen sent a letter to the president on Oct. 14 expressing dismay over the civilian casualties, including reports that Saudi-led airstrikes had killed more than 150 Yemenis attending two separate wedding parties.

"We are concerned that some overseas may hold the United States responsible for any civilian casualties resulting from the bombing," the House members wrote.

An Amnesty International report over the summer raised the possibility that all sides in the Yemen conflict had committed war crimes. But facing Saudi resistance, the U.S. and other Western governments recently dropped support for a U.N. resolution to allow an independent investigation of human rights violations in Yemen; instead, to the dismay of rights activists, they backed a resolution that would let the Yemeni government led by Hadi oversee an inquiry, though with U.N. assistance.

Representatives of the Saudi government did not respond to requests for comment, but the State Department official questioned some of the reporting on civilian casualties, saying, "There have been occasions where assertions are made that the Saudis bombed something, and we’re pretty confident based on our own information that they are not true."

Administration officials note that the Houthis are hardly blameless when it comes to civilian misery. They also insist the U.S. isn't to blame for civilian casualties because it doesn't pick the targets.

"There is a clear distinction between logistical and intelligence support, which we have provided, and taking part in targeting decisions, which we do not do," a senior administration official said.

That may be a distinction without a difference, said Barbara Bodine, a former U.S. ambassador to Yemen. "This is our military equipment," Bodine said of the ongoing Saudi-led campaign. "It’s talked about in the region as the 'Saudi-American' air campaign. It’s seen on Al Jazeera that way ... You can’t say you’re giving them a menu of targets and then they pick the wedding party. Implicitly, if you gave them the menu of targets and the wedding party was on it, then you gave them the wedding party."

Even still, Arab and U.S. officials argue the situation could be worse if the U.S. wasn't involved. For one thing, without the guidance of the U.S., the Saudi-led units could make even more mistakes.

"The Americans are in very close cooperation with coalition countries, and the help they provide could help us avoid a lot of casualties," said an Arab official familiar with the events in Yemen. "My understanding is it’s helping in stabilizing the situation."

An Obama administration official familiar with the Yemen debate stressed that any internal divisions in the administration were minor compared to the frustration the U.S. has felt with the Saudis.

"The one thing that matters is where the president is, and the president has conveyed personally his concern about the humanitarian issues to his Saudi counterpart," the official added.

Even before the Saudi-led campaign began, the U.S. had a bad reputation in Yemen when it came to civilian deaths due to drone strikes that have targeted Al-Qaeda’s affiliate. The perception that the U.S. is behind the civilian deaths as part of the Saudi-led campaign could further feed support for such jihadist groups. While the Islamic State has made some gains in Yemen, the last seven months of fighting have mainly benefited Al-Qaeda in the Arabian Peninsula, counter-terrorism analysts said.

"With the focus of the current fighting pitting Houthi forces against anti-Houthi forces, AQAP is largely being ignored," wrote Martin Reardon, a senior vice president with The Soufan Group. "In fact, AQAP has actually been able to strengthen its tribal support in the central region and expand its area of operations significantly in the last several months — to include taking control of Al-Mukalla, Yemen’s third largest port."

Saudi Arabia's determination to send a message to Iran via Yemen could be fueled by the kingdom's domestic politics. Saudi King Salman ascended to the throne just two months before the military campaign was launched. The operation is being overseen by his 30-year-old son, Mohammed bin Salman, who is second in line to the throne but rumored to be eager to get the crown quicker. To prove his mettle, he has to achieve some sort of victory in Yemen, where tribal loyalties have long bedeviled interlopers.

At this point, it's anyone's guess what kind of victory that might be.

"Even if the Saudis and their allies are able to militarily push the Houthis up into the mountains or something, as we know from our own history, you can win on the battlefield and still lose the war," Bodine said.