The Biden administration is expected to use drone warfare in Afghanistan after the U.S. military evacuated the country on Tuesday to bring an end to America’s longest war.

President Joe Biden gave his military commanders authorization to carry out drone strikes against ISIS-affiliated targets who are responsible for killing 13 U.S. service members in a terrorist attack at the Kabul airport. Biden vowed vengeance for the attacks, saying “We will not forgive. We will not forget. We will hunt you down to the ends of the earth, and you will pay the ultimate sacrifice.”

A drone attack carried out on Friday in Jalalabad killed two militants and injured a third individual, and a Sunday strike destroyed an ISIS-K car bomb, sending a message to militants that military action will likely persist in the country despite no troops remaining on the ground.

“To ISIS-K: We are not done with you yet,” Biden said in a speech at the White House on Tuesday, vowing a “tough, unforgiving, targeted, precise strategy.”

“There’s not many tools left in the tool kit if we don’t have people on the ground,” said Barry Pavel, director of the Atlantic Council’s Scowcroft Center for Strategy and Security.

The increased drone presence will make civilian casualties more likely as 90% of those killed by drone strikes are civilians. That reality was sadly demonstrated on Sunday when 10 civilians, including 6 children under the age of 10, were killed in the retaliatory strike.

The lack of military personnel in Afghanistan will require drones to be flown in from outside the country, requiring more resources to maintain them. “If you’re launching a drone from in-country, you launch it, it does its thing and you recover it. If you’re launching it from farther away, it requires a lot more maintenance, sustainment. It deteriorates equipment more, it’s a significant resource drain,” Pavel said.

Drone use was the preferred method of the Obama administration in order to avoid sending U.S. troops into combat zones. Obama also tallied all military-aged males in strike zones as combatants, thus lowering the overall death toll as recorded by the Pentagon. During Obama’s eight years as president, he carried out 1,878 drone strikes.

When Donald Trump was president he massively increased the number of drone strikes as his administration carried out 2,243 as of March 2019.

Pavel has stated it is unclear whether or not Biden will increase drone strikes in the region since “it depends on the trend of violence.”