The United States has conducted at least 190 armed actions, mostly airstrikes, in Yemen since President Trump took office in 2017, resulting in a minimum of 86 likely civilian deaths, a new study by a watchdog group has found.

The analysis by Airwars, a Britain-based organization which uses local news, social media and civil society reports to corroborate claims of civilian harm, provides new insight into a war that has been largely shrouded in secrecy. The U.S. attacks, which Airwars said were carried out primarily by the U.S. military and included a handful of ground raids, appeared to represent the most intensive period of American counterinsurgent activity in Yemen since 2001, the study said.

Airwars urged U.S. military authorities to investigate allegations of noncombatant deaths and disclose more information about the actions it mounts against militants in Yemen, the same way it has in the U.S.-led war against the Islamic State in Iraq and Syria.

The failure of U.S. Central Command (Centcom), which oversees military operations in the Middle East, “adequately to identify, review and where necessary acknowledge civilian harm claims from its actions in Yemen appears to be markedly at odds with current Pentagon policies, and should be addressed as a matter of urgency,” Airwars said.

A Centcom spokesperson did not provide an immediate comment on the Airwars study. But in its annual reports to Congress on civilian casualty investigations for 2018 and 2019, the Pentagon said there were no reported civilian casualty incidents in Yemen. All told, the U.S. military has acknowledged only up to a dozen possible civilian casualties in Yemen during Trump’s presidency.

The study comes as the Trump administration seeks to wind down counterinsurgent operations across the Middle East and Central Asia in keeping with the president’s desire to refocus resources at home and the Pentagon’s planned pivot to China.

The administration is currently reducing forces in Afghanistan and Iraq, and fewer than 1,000 troops remain in Syria.

The allegations provide new information about one dimension of the conflict gripping Yemen. While the United States and the United Arab Emirates continue to periodically target al-Qaeda in the Arabian Peninsula and the local Islamic State branch, a mostly unconnected war has consumed much of the country since 2015. In that larger conflict, Houthi rebels backed by Iran have battled forces representing Yemen’s internationally recognized government, which is supported by a Saudi-led military coalition.

According to Airwars, the vast majority of the armed actions that occurred in Yemen during Trump’ s presidency took place in 2017. The first was an ill-fated raid that occurred days after Trump’s inauguration. The operation, involving elite American and Emirati forces, resulted in the death of a Navy SEAL and a number of civilians deaths.

The raid is the only event during the Trump administration for which the U.S. government has acknowledged the possibility of civilian casualties. While military officials put the estimate of noncombatants who died at up to 12, Airwars believes the number was at least 20.

In addition to airstrikes, Airwars cited two other raids in 2017, both of which the group said appeared to result in civilian casualties.

Airwars said the military has not stood up a team responsible for investigating civilian casualty investigations, as it did for Iraq and Syria. That operation, which included tens of thousands of strikes, has included regular reporting on airstrikes and steps to increase transparency surrounding unintended civilian injury and death.

According to Centcom, the last U.S. military strike that occurred in Yemen took place in June 2019. But Airwars said a smaller number of strikes since then appear to have been conducted by the CIA or were the product of clandestine military activity.

Those include a February 2020 “counterterrorism operation” targeting Qasim al-Rimi, and another targeted Abdullah al-Maliki, who was believed to be linked to a man who shot U.S. service members at a military base in Pensacola, Fla.

“From mid 2019 onwards, covert and clandestine actions in Yemen appear to have dominated US engagements, Airwars research shows — with troubling implications for civilian harm accountability,” Airwars said.

The CIA did not immediately comment.

While most of the incidents cited by Airwars appear to have targeted militants associated with al-Qaeda in the Arabian Peninsula or the Islamic State, one attack took aim at a senior Iranian official operating in Yemen. The strike, which targeted a senior Islamic Revolutionary Guard Corps operative named Abdulreza Shahlai, did not succeed.