By Wednesday night, US intelligence agencies were near certain that an attack was imminent outside Kabul airport, triggering a warning to American citizens to leave the area immediately.
Just 12 hours later, suicide bombers walked through the large crowds to a gate manned by US troops and detonated explosives, killing at least 162 Afghans and 13 US service members.
It was a tragic coda to America’s 20-year war in Afghanistan, the largest loss of life for the US military there in a decade, on the cusp of the full withdrawal of troops by August 31 ordered by President Joe Biden.
Among the most pressing questions as the US military launches its investigation: How did the bomber make it through Taliban checkpoints? Why were US troops in such a concentrated space when they knew an attack was imminent?
“It was a failure somewhere,” General Frank McKenzie, the head of US Central Command, told reporters hours after the attack, which was claimed by an ISIL offshoot in Afghanistan – the Islamic State in Khorasan Province, ISKP (ISIS-K).
But at some point, McKenzie added, troops had no choice but to come in contact with people trying to board evacuation flights, screen them, pat them down for weapons and ensure they did not make it into the airport if they posed a threat.
US officials, speaking on condition of anonymity, said the conditions for the attack were set months in advance.
They told Reuters news agency that weeks before the evacuation from Kabul airport began following the Taliban’s takeover of the capital, the military had been seeking approval to get at-risk Afghans out of the country.
But the slow tempo of processing and inability to secure housing for the evacuees in third countries slowed down the pace of departures, according to the officials, at one point halting all flights from Kabul for six hours.
That meant troops were on the front lines at the airport gates in the face of chaos outside.
“This didn’t need to happen,” a US military official said. “They didn’t need to die.”