As many as 12 civilians died in a raid against al Qaeda in Yemen in late January, the head of the U.S. military's Central Command said on Thursday. "We have made a determination based on our best information available that we did cause ... between four and 12 casualties," U.S. Army General Joseph Votel told a Senate hearing, adding he accepted responsibility for shortcomings in the operation.

Critics have questioned the value of the raid against al-Qaida in the Arabian Peninsula, authorized by President Donald Trump, in which U.S. Navy SEAL William "Ryan" Owens also died.

The Pentagon said it is carrying out an investigation into the details surrounding Owens' death and another review into the destruction of a U.S. military helicopter in the operation.

Votel said a separate, "exhaustive after-action review" had not found incompetence, poor decision-making or bad judgment. "As a result, I made the determination that there was no need for an additional investigation into this particular operation," Votel said.

The United States has conducted more than 40 strikes against Al-Qaeda in Yemen since stepping up its air war against the jihadists last Thursday.

The International Crisis Group think-tank has warned that operations like the Baida raid risk fanning hostility towards the United States among civilians, providing fertile ground for recruitment by Al-Qaida.

Yemen is of critical importance to the U.S. as the country is home to one of America's biggest enemies: Al-Qaida, as well as its deadliest franchise, al-Qaida in the Arabian Peninsula (AQAP), which orchestrated numerous high-profile terror attacks, including the Charlie Hedbo massacre in Paris, France. Since 2012, the U.S. has launched counterterror airstrikes and operations against radical militants as part of the U.S. national security policy. The U.S.'s "targeted-killing policy" and other practices by the Obama administration have raised serious concerns regarding the rule of law, war crimes and the human cost of the U.S. security policy in Yemen.

Iran-backed Houthi rebels seized the Yemeni capital Sanaa in September 2014, forcing the internationally recognized government to flee the country. A Saudi-led, U.S.-backed coalition has been conducting an extensive air campaign against the Houthis since March 2015 that has pushed the rebels out of southern Yemen. The U.N. says the conflict has left more than 19,000 people dead and displaced at least 3 million. Saudi Arabia leads a coalition of Muslim countries, backed by the U.S., the U.K. and France, in the war in neighboring Yemen. The campaign, which is a campaign to restore the government ousted by the Iran-allied militia, is part of a larger assertive effort to prevent weapons from reaching Shiite Houthi rebels and their allies, who have overrun much of Yemen.