A U.S. service member killed during combat operations in Afghanistan on Thursday is the 18th fatality for Operation Freedom's Sentinel so far in 2019, defense officials said.

The name of the latest service member killed is being withheld pending next of kin notification.

A total of 15 U.S. troops have been killed in combat in Afghanistan this year.

Two other service members died in non-combat incidents and a sailor from the USS Abraham Lincoln was declared dead after falling overboard in the Arabian Sea while the carrier was supporting operations in Afghanistan.

At least two other Americans have also died in Afghanistan in 2019. Both were military veterans working as defense contractors.