Editor's Note: Thursday evening the Pentagon provided an updated tally of fatalities tied to the bombings at Hamid Karzai International Airport, bringing the total to 13 U.S. service members. This story has been updated accordingly.
The Pentagon is expecting more attacks after a bombing Thursday at Kabul's Hamid Karzai International Airport killed 13 U.S. service members and scores of Afghan civilians in one of the deadliest days of the 20-year war. A further 18 American troops were wounded.
With less than a week remaining before the Aug. 31 deadline to complete the withdrawal of U.S. troops from Afghanistan, defense officials say they're developing plans to strike back against those responsible for the attack, which included two suicide bombers and gunfire.
"We are working very hard right now to determine attribution, to determine who is associated with this cowardly attack, and we're prepared to take action against them," Marine Gen. Kenneth McKenzie, head of U.S. Central Command, told reporters Thursday afternoon.
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An Islamic State affiliate, ISIS-Khorasan or ISIS-K, is largely seen as the most likely culprit, given prior intelligence warnings about planned attacks against the airport.
The situation on the ground is incredibly fragile, as the U.S. has an effective alliance with the Taliban for the time being and is sharing redacted intelligence to prevent attacks from ISIS-K.
McKenzie said that the U.S. military is "reaching out to the Taliban" as they provide security on the outskirts of the airport, outside of the American-controlled area.
"Despite this attack, we're continuing the mission. The threat from ISIS is extremely real," McKenzie said. "We believe it is their desire to continue the attacks, and we expect the attacks to continue. We're doing everything we can to prepare for those attacks."
The Taliban, which has fought against the U.S. for two decades, recently conquered Afghanistan. But the group is also in a war with ISIS-K, a longtime rival.
McKenzie said the Taliban are eager to see U.S. forces leave and are motivated to make the withdrawal go smoothly. He added there is so far no evidence the Taliban purposefully let the suicide bombers slip through searches.
"We share a common purpose," McKenzie said. "They've been useful to work with."
Just weeks ago, the U.S. and Taliban were staunch enemies who had spent decades killing one another. The U.S. initially invaded Afghanistan to overthrow the Taliban government, but the group reclaimed that role with little resistance in recent weeks. Now, U.S. officials find themselves negotiating with their former foe to try to evacuate Americans and American allies safely.
McKenzie said the Pentagon asked the Taliban to broaden the security perimeter outside the airport and close down a series of roads after the attack. The U.S. also is flying attack aircraft around Kabul to deter would-be attackers, hoping planes and attack helicopters could quickly identify and strike anyone who attacks the airfield.
Thursday's attack consisted of two suicide bombers. One bomb was detonated near an airport gate in a packed crowd of Afghans desperately trying to flee the country, many of whom fear retribution from the Taliban for working with the U.S. or the now-collapsed Afghanistan government.
The second bomb was set off at a hotel across the street from the airport. Gunfire followed the explosions, but it is unclear whether U.S. troops were able to return fire.
"We mourn their loss. We will treat their wounds. And we will support their families in what will most assuredly be devastating grief. But we will not be dissuaded from the task at hand," Defense Secretary Lloyd Austin said in a statement. "To do anything less -- especially now -- would dishonor the purpose and sacrifice these men and women have rendered our country and the people of Afghanistan."
-- Steve Beynon can be reached at Steve.Beynon@military.com. Follow him on Twitter @StevenBeynon.