The U.S. military said it conducted an airstrike against Islamic State in Afghanistan on Saturday, likely killing an extremist leader described as a planner for the organization.

The strike was its first known U.S. response to Thursday’s suicide bomb attack outside the airport in Kabul that killed 13 American troops and nearly 200 Afghan civilians.

Navy Capt. Bill Urban, a spokesman for U.S. Central Command, which oversees U.S. forces in the Middle East and Afghanistan, said it was an “over-the-horizon” strike, meaning the unmanned aerial vehicle used in the operation flew from a site outside of Afghanistan.