U.S. Africa Command on Friday, April 5 admitted that an airstrike last year aimed at the insurgent group al-Shabaab in Somalia killed two civilians and that it previously failed to properly disclose its findings.

The April 1, 2018 airstrike was aimed at Shabaab near El Burr in central Somalia, but an internal review concluded last month found that two civilians were killed, Africom said in a press release.

“On March 30, 2019, the command was notified about the results of a post-strike internal assessment conducted in April 2018 that found credible evidence of the two civilian casualties. Unfortunately, the finding was not properly reported to U.S. Africa Command headquarters,” the release said.

Four al-Shabaab militants were also killed in the strike, the command said.

“Because of the reporting error, U.S. Africa Command was not informed of the assessment’s conclusion-and subsequently the information was not reported to external authorities, such as the host nation and Congress,” Africom said Friday.

Africom’s initial report of the airstrike said it had killed five al-Shabaab fighters and no civilians.

The error was compounded when senior leaders said during congressional testimony that U.S. forces had caused zero civilian casualties in Africa.

Africom commander General Thomas D. Waldhauser had ordered a review of airstrikes conducted in Somalia since 2017 “due to a recent increase in airstrikes and continued interest by Amnesty International and Congress on civilian casualties,” the release said.

The April 2018 airstrike was not one presented by Amnesty International in its report last month on U.S. actions in Somalia.

Africom at the time disputed the rights group’s allegations, insisting that everyone killed in the strikes were legitimate targets.

“Since June 2017, Africom conducted 110 airstrikes in Somalia, eliminating more than 800 terrorists,” it said in a statement, adding that “our assessments found that no Africom airstrike resulted in any civilian casualty or injury.”

Africom added that it was “in the interest of the terrorist group al-Shabaab to untruthfully claim civilian casualties.”

Amnesty had accused the command of possibly violating international law, and saying some of the airstrikes it documented “may amount to war crimes.” Its investigation revealed that 14 civilians were killed, raising fears that the true death toll may be much higher.

“Credibility, transparency, and accountability are fundamental to military operations,” Waldhauser said on Friday. “It is critically important that people understand we adhere to exacting standards and when we fall short, we acknowledge shortcomings and take appropriate action.”

Africom says it has carried out 28 airstrikes in Somalia in 2019, compared to 47 in 2018 and 35 in 2017.

U.S. strikes in Somalia surged in April 2017, after President Donald Trump declared southern Somalia an “area of active hostilities,” Amnesty said last month.

Al-Shabaab is fighting to overthrow the internationally backed government in Somalia, but has also carried out attacks in neighboring Kenya, which has deployed troops as part of the African Union Mission in Somalia.

The group was routed from Mogadishu in 2011 by the 22,000-strong African Union mission AMISOM, and has had to abandon most of its strongholds, but it still controls vast rural areas and remain the key threat to peace in Somalia.

U.S. forces partner with Somali national security forces in counterterrorism operations, and have conducted frequent raids and drone strikes on al-Shabaab training camps throughout Somalia.

The Somali government was notified of the civilian casualties, and U.S. Africa Command said it “remains in close coordination with our partners.”