US Senators Chris Murphy and Elizabeth Warren have demanded that the Pentagon conduct further investigations into civilians killed as a result of US military operations in Yemen.

In a letter published in Middle East Eye, the two Democrats said the current administration should properly investigate "credible reports of civilian harm, including those from Yemen."

New investigations, according to Murphy, a member of the Senate Foreign Relations Committee, and Warren, a member of the Armed Services Committee, should involve site visits, interviews with witnesses, and information from sources other than the US military.

In the Tuesday letter, they urged the administration to "open new investigations into reports of civilian harm from U.S. military operations in Yemen raised by credible NGOs or external sources, to report publicly and transparently on your conclusions, and to take appropriate steps toward redress and accountability."

"The consequences of U.S. military operations in Yemen have been deep and long-lasting for scores of Yemeni civilians. We look forward to learning how you will work to provide transparency, accountability, and justice for those harmed."

According to the Yemen-based rights group Mwatana for Human Rights and the Columbia Law School Human Rights Clinic, 38 people were killed in 12 US operations between 2017 and 2019, including 13 children. Seven more civilians, including six children, were wounded. 

The operations, which comprised ten airstrikes and two ground attacks, constitute a sample of the more than 500 US airstrikes documented in Yemen since 2009.

Previously, when rights groups gave US Central Command (Centcom) 150 pages of data demonstrating proof of civilian injury, the US military replied by rejecting civilian deaths in all but two of the instances, as well as any civilian injuries.

It also stated that compensation for victims was "not appropriate" in both of the incidents it recognized.

Senators demanded that the Pentagon "provide greater transparency into current military review processes, including how reports from credible NGOs or external sources are received and reviewed."

The Saudi-led coalition has conducted over 22,000 airstrikes on Yemen, including schools, factories, weddings, and hospitals.

Last year, the Biden administration claimed it ended its support of the Saudi-led coalition last year, but Democrat lawmakers have demanded that US President Joe Biden clarify the role of the United States in Yemen, in addition to the forms of support Washington is offering the Saudi-led coalition in its war on the country.

For the last two decades, the United States military has tried to address the issue of civilian deaths in its operations throughout the Middle East and Asia.

According to Brown University's Costs of War Project, tens of thousands of people have been directly murdered in the carnage of Washington's post-9/11 conflicts.

The topic has resurfaced in the last year, following the August death of an aid worker and nine members of his extended family by a US drone attack.

In November, Biden approved a $650 million arms sale to Saudi Arabia, which comprises 280 AIM-120C-7/C-8 Advanced Medium-Range Air-to-Air Missiles (AMRAAM), 596 LAU-128 Missile Rail Launchers (MRL) along with containers and support equipment, spare parts, US Government and contractor engineering, and technical support.

Saudi military purchases from US sources and firms are estimated at $63 billion since its aggression on Yemen, adding the collective contracts stipulated with US firms in which Saudi Arabia "was clearly the primary buyer."

Deeply flawed intelligence 

In November, The New York Times studied 1,311 documents from a hidden Pentagon archive, concluding that the civilian death toll was a lot higher than the 1,417 civilian deaths reported by the US military in Iraq and Syria and the 188 deaths reported in Afghanistan.

Thousands of civilians, including children, were murdered by US airstrikes in Iraq, Syria, and Afghanistan, according to The New York Times, which were carried out with imprecise targeting and "deeply flawed intelligence."

The publication had also reported that a secret US strike cell called Talon Anvil was responsible for civilian casualties in Syria resulting from airstrikes.

DoD not fit to deal with civilian casualty reports: Assessment

In January, according to key findings of a Department of Defense (DoD) civilian casualties and procedures assessment, the data and records kept by the US military to support evaluations of civilian injury may be incomplete.

The military's criteria for determining the credibility of a civilian fatality is greater than it claims. Furthermore, combat commanders that are preparing for high-intensity combat against near-peer opponents are unprepared to deal with civilian-harm problems.

"When there is little policy change or accountability for repeated mistakes this grave and this costly, it sends a message throughout the U.S. Armed Forces and the entire U.S. government that civilian deaths are the inevitable consequence of modern conflict, rather than avoidable and damaging failures of policy," the lawmakers said.