WASHINGTON: Eight US service members were injured in a drone attack on a base in Syria last week, the Pentagon said on Tuesday, its first report of specific casualty figures in the incident. Reuters first reported that several US and coalition personnel were wounded in a drone attack on Friday at Rumalyn Landing Zone, which hosts troops from the US and other countries in the US-led coalition. Pentagon spokesperson Air Force Major General Patrick Ryder told reporters on Tuesday that three personnel had already returned to duty. The eight troops were treated for traumatic brain injury and smoke inhalation. The US says its 900 troops in Syria and 2,500 in neighboring Iraq are advising and assisting local forces trying to prevent a resurgence of Islamic State, which in 2014 seized large swaths of both countries but was later pushed back. Ryder added that the US believed that the attack was carried out by Iran-backed forces, but the Pentagon was working to determine which one.