Milliken, 38, was killed Thursday in a remote area approximately 40 miles west of the capital Mogadishu as U.S. forces were conducting an advise-and-assist mission with members of the Somali National Army. The group came under attack in the middle of the night.
“We helped bring them in there with our aircraft,” Pentagon spokesman Capt. Jeff Davis told reporters Friday. “We were there maintaining a distance back as they conducted the operation, that’s when our forces came under fire and we had the unfortunate casualty.”
U.S. and Somali forces were ultimately able to return fire and suppress the attack, a U.S. official told ABC News.
No Somali forces were hurt but a Somali interpreter and two U.S. service members were injured.
The United States has about 50 military personnel in the country, Davis said.
The mission was not being carried out under the new expanded authorities granted by the Trump administration for the U.S. military to conduct offensive counterterrorism airstrikes in Somalia targeting al-Shabab, according to the U.S. official.
"Al-Shabab presents a threat to Americans and American interests," U.S. Africa Command said in a statement on Friday. "Al-Shabab's affiliate, al-Qaeda has murdered Americans; radicalizes and recruits terrorists and fighters in the United States; and attempts to conduct and inspire attacks against Americans, our allies and our interests around the world, including here at home.
"U.S. forces are assisting partner forces to counter al-Shabab in Somalia to degrade the al-Qaeda affiliate's ability to recruit, train and plot external terror attacks throughout the region and in America," the statement added.
Ultimately, al-Shabab decided not to affiliate itself with ISIS, although a small faction did break away and pledge its allegiance.