Hours after U.S. service members were killed and at least 15 wounded in terrorist bombings in Afghanistan, President Joe Biden defended his decision to withdraw troops from the country and told those responsible for Thursday’s attack: “We will hunt you down.”

“I will also order my commanders to develop operational plans to strike ISIS-K assets, leadership, and facilities,” Biden said in a televised speech to the nation. “We will respond with force and precision at our time, at the place that we choose, at the moment of our choosing.”

At least 13 members of the U.S. military were killed in the bombings at the airport in Kabul, where thousands have been attempting to escape the country. ISIS-K, the Islamic State in Khorasan, is believed to be behind Thursday’s attacks

The Taliban, an Islamic militant organization, took control of much of Afghanistan just days after Biden’s decision to withdraw U.S. troops after 20 years of war in the wake of the Sept. 11, 2001, terrorist attacks on U.S. soil that killed nearly 3,000 Americans. Biden has been widely criticized for the quick withdrawal and the chaotic evacuation of U.S. citizens and others from Afghanistan.

Biden said the U.S. has “some reason to believe we know who they are” when referring to the attackers, adding “we’re not certain.”

The president said he was willing to authorize more troops if military officials needed it and defended relying on the Taliban to keep the Kabul airport where the attacks occurred secure. The Taliban and ISIS-K publicly say they are enemies.

Also on Thursday, General Kenneth McKenzie said ISIS-K is expected to continue their attacks.

“The threat from ISIS is very real,” he said. “We have been talking about this for several days. We saw it actually manifest itself here the last few hours with an actual attack. We believe it is their desire to continue those attacks, and we expect the attacks to continue. We are doing everything we can to be prepared for those attacks.”

McKenzie also said there are more than 1,000 Americans remaining in Afghanistan and that U.S. forces had so far screened more than 100,000 people attempting to evacuate the nation, which was taken over by the Taliban within only a few days.

“Our mission is to evacuate U.S. citizens, nationals, special immigrant visa holders, embassy staff, and Afghans at risk,” McKenzie said. “Despite the attack, we are continuing the mission. There are approximately 5,000 documents awaiting airlift. We have evacuated more than … over 66,000 from the United States and 37,000 by our allies. That includes bringing out about 5,000 Americans.”

Biden also praised the heroism of those killed and wounded in Thursday’s attack.

“They were heroes,” Biden said. “Heroes who’ve been engaged in a dangerous, selfless mission to save the lives of others.”

This article was originally posted on Biden defends Afghanistan withdrawal, pledges to hunt down terrorists who killed 13 U.S. military members