In the wake of the U.S.-backed Saudi-led coalition's horrific bombing of a school bus last week that killed 40 Yemeni children and amid reports on Tuesday of dozens more civilian deaths after a new wave of Saudi bombings, Rep. Ted Lieu (D-Calif.) has sent a detailed letter (pdf) to the Department of Defense Inspector General demanding an investigation into whether Trump administration officials violated U.S. or international law by assisting the Saudis in their assault on Yemen.

"It is indisputable that the DoD-supported coalition has killed large numbers of children, women, and men who are civilians."

—Rep. Ted Lieu

The Saudi-led coalition, which receives essential military support and intelligence from the U.S., "has repeatedly hit civilian targets—including schools, hospitals, funerals, and weddings—nowhere near military targets," Lieu writes, pointing to an analysis by the Yemen Data Project showing that a third of Saudi bombings in Yemen have hit civilian targets. "I previously served on active duty as a JAG [Judge Advocate General] and a number of the coalition's airstrikes look like war crimes."

"If the coalition's targeting of farms, food storage sites, and water sites was deliberate, these airstrikes would constitute a violation of Article 14 of Additional Protocol II and customary international law in non-international armed conflict," Lieu adds. "I am deeply concerned that continued U.S. refueling, operational support functions, and weapons transfers could qualify as aiding and abetting these potential war crimes."

The California congressman goes on to note that the U.S.-backed Saudi attacks on civilian targets cannot be attributed to mere faulty intelligence or incompetence.

"The coalition, which has air superiority, has in a number of cases very precisely struck civilian targets," Lieu notes. "For example, coalition jets precisely struck a funeral attended by a large number of people and then came around and struck the same civilian target again. It is indisputable that the DoD-supported coalition has killed large numbers of children, women, and men who are civilians."

In a letter (pdf) of her own on Tuesday, Sen. Elizabeth Warren (D-Mass.) called on Gen. Joseph Votel—the top commander of U.S. forces in the Middle East—to explain the U.S. military's role in the Saudi-led coalition's bombings of Yemeni civilians.

"According to public reports and non-governmental organizations operating on the ground in Yemen, coalition airstrikes, including some that are likely to have been supported by U.S. refueling and supplied with U.S. munitions, have resulted in the deaths of thousands of Yemeni civilians since the beginning of the military campaign in 2015, including most recently a school bus carrying dozens of children," Warren noted.

Lieu and Warren's letters come as Yemen-based journalists reported that yet another Saudi-led bombing campaign in the port city of Hodeidah on Tuesday killed more than 30 people, including women and children.

#Breaking: #Saudi led coalition airstrikes on Alduraihimi town in #Hodeidah killed 33 and injured 22 including women and children.#Yemen. — Ahmad Algohbary (@AhmadAlgohbary) August 14, 2018 Please world wake up & talk about #Yemen

A new massacre committed today by Saudi airstrikes on civilians.

At least 25 people have been killed & wounded, icluding children & women in raids by Saudi regime on homes and markets in al-Durehimi area of #Hodeidah in western #Yemen — Fatik Al-Rodaini (@Fatikr) August 14, 2018 Just 5 days after a US-backed coalition airstrike hit a school bus full of kids, another air strike hits Hodeidah, Yemen, killing more civilians. Your tax dollars at work. #OpDeSanitize https://t.co/cVRjeGC97E — Walker Bragman (@WalkerBragman) August 14, 2018

Since the U.S.-backed Saudi coalition's bombing of a school bus last week, journalists and human rights advocates have denounced the attack as a clear war crime and demanded to know precisely what role the U.S. played in the massacre.

"For the Saudi-led coalition to bomb a bus full of children is a war crime."

—Shireen Al-Adeimi

As Democracy Now! noted in a segment Tuesday morning, images posted to social media suggest that the bomb used in the attack was a Mark-82, which is manufactured by the massive American defense contractor Raytheon.

While U.S. Secretary of Defense James Mattis has dispatched an American general to assist the Saudis with its "investigation" into the school bus bombing, Shireen Al-Adeimi—a human rights activist and professor at Michigan State University—told Democracy Now! that it is "preposterous to think" that the Saudis can properly investigate their own crimes, particularly given that one Saudi official has already described the school bus as a "legitimate target."

"For the Saudi-led coalition to bomb a bus full of children is a war crime"

-Yemeni scholar and activist @shireen818 on last week's US-backed Saudi-UAE coalition strike on schoolchildren in #Yemenhttps://t.co/QzzC9Mzl47 pic.twitter.com/xuqUcYmy05 — Win Without War (@WinWithoutWar) August 14, 2018

"Every single day, there are airstrikes and casualties and civilians who have been killed by Saudi-led airstrikes. They have essentially absolved themselves of all wrongdoing every time they have investigated themselves," Al-Adeimi concluded. "What Yemenis need is really an independent investigation, which has been put forward in the U.N. twice already and has been rejected by the Saudi-led coalition and the U.S. unfortunately has provided cover for the Saudi-led coalition at the U.N."

Watch Al-Adeimi's full interview on Democracy Now!: