Four U.S. special operations troops were hurt when an Islamic State rocket landed near their position in northern Syria earlier this month, bringing renewed questions about the role of U.S. troops in the region, specifically special operations forces serving alongside indigenous troops fighting ISIS.

A senior defense official told Fox News the U.S. troops were “lightly” wounded and quickly returned to duty.

To date, the Pentagon reports 16 U.S. troops have been wounded and three killed in hostile action against ISIS since President Obama authorized the first deployment of U.S. military forces back to Iraq in June 2014.

Pentagon statistics show 15 U.S. troops have been killed in non-combat incidents in the Middle East as part of the anti-ISIS coalition.