Commander of the United States Central Command Gen. Kenneth McKenzie told reporters Thursday that the U.S. expected to be attacked “sooner rather than later” following a deadly terror attack in Kabul, Afghanistan.

Suicide bombers attacked the throngs of people just outside of the Kabul airport, killing at least 12 U.S. service members and injuring at least 15 others. The number of injured and dead Afghans remains unknown. Hours after the attack, McKenzie spoke to reporters at the Pentagon press briefing, announcing the evacuation mission will continue and admitting the attack wasn’t a surprise.

“I will tell you this,” McKenzie said. “Anytime you build a non-combatant evacuation plan like this and you bring in forces, you expect to be attacked. We expected … We thought it would happen sooner rather than later. It’s tragic that it happened today.”

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McKenzie continued on to say that they “are prepared to continue the mission.” He explained that “a number of ISIS gunmen … opened fire” after the “two suicide bombers assessed to have been ISIS fighters detonated near” one of the gates at the Baron Hotel and warned that this may not be the last attack. (RELATED: 12 US Troops Killed, 15 Injured In Kabul Attacks, Pentagon Confirms)

“First of all, the threat from ISIS is extremely real,” he said. “We believe it is their desire to continue those attacks and we expect those attacks to continue and we’re doing everything we can to be prepared for these attacks. That includes reaching out to the Taliban who are providing the outer security cordon to make sure they know what we expect them to do to protect us. We are continuing to bring people on to the airfield.”

“The plan is to continue to operate while under stress and under attack and we will continue to do that. We will coordinate very carefully to make sure it’s safe for American citizens to come to the airport. If it’s not, we’ll tell them to hold and we’ll work other ways to try to get them to the airport,” McKenzie added.

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President Joe Biden is sticking with the Aug. 31 withdrawal deadline, although G7 allies urged him to extend it. The administration has previously warned about the possibility of attacks on the ground.