President Joe Biden has vowed revenge on the terrorists who killed US troops and Afghan civilians - including children - in a devastating twin bombing in Afghanistan.
The US leader at first appeared deflated as he addressed Americans to hail the "heroes" who lost their lives in the effort to help Afghans trying to flee.
He then made a rousing tribute to the troops killed, before threatening to hunt down their killers and holding a visibly emotional minute's silence.
The president vowed revenge on the culprits who claimed to be behind the day's attacks, warning ISIS-K: "We will not forgive, we will not forget, we will hunt you down and make you pay."
Mr Biden faced a grilling as he addressed Americans after 12 US troops and dozens of Afghans died in twin bombings that ripped through the capital.
He fronted Thursday's White House press conference under immense pressure over his handling of the US withdrawal.
Mr Biden at first recalled the pain of his son's own death as he acknowledged America's deadliest day in a decade in Afghanistan.
"You get this feeling like being sucked into a black hole in the middle of your chest," he told the Marines' grieving families. "No way out. My heart aches for you."
But grilled about his own role in the lead-up to the carnage, Mr Biden insisted he stood by his decision to withdraw.
He finished the press conference by declaring: "Ladies and gentlemen, it's time to end a 20-year war."
It was a dark day for US forces, which suffered their highest death toll in a single day since August 2011, when 30 personnel were killed after a helicopter was shot down.
And it was yet another day of horror for Afghans trying to flee the country.
Suicide bombers targeted an area outside the Hamid Karzai International Airport where desperate people were gathered in a bid to escape Taliban rule.
Bombers struck sitting targets - Afghans clustered together in a sewage canal in hopes of salvation along with the the troops securing the site, sparking devastating scenes of mass casualties.
The crowds were targeted as the hours ticked down toward an August 31 deadline for US forces to withdraw from the country.
Terror group affiliate ISIS-K claimed responsibility for the attacks and identified the bomber behind the blast at Abbey Gate as Abdul Rehman Al-Loghri.
The Taliban said some of its guards were also killed in the blasts, as it condemned the violence targeting crowds trying to flee its own rule.
Mr Biden told Americans the US found itself needing to coordinate with Taliban personnel on the ground, but added his stance remained that "they're not good guys."
He added in response to reporters: "I bear responsibility for, fundamentally, all that's happened of late. But here's the deal: You know, I wish you'd one day say these things, you know as well as I do, that the former president made a deal with the Taliban."
The explosions tore through crowds that have thronged the Kabul airport gates desperate to leave Afghanistan since the Taliban seized power almost two weeks ago.
The Ministry of Defence said no UK military or other personnel were hurt in the attack.
The US military death toll in the Afghanistan war since 2001 stood at roughly 2,500 before the latest round of bloodshed.
The attacks came after the US and allies urged Afghans to leave the area around the airport because of a threat by ISIS militants.
In a statement, ISIS claimed responsibility and said one of its suicide bombers had targeted "translators and collaborators with the American army".
The US and its allies have mounted one of the biggest air evacuations in history, bringing out about 95,700 people, including 13,400 on Wednesday, the White House said on Thursday.
A massive airlift of foreign nationals and their families, as well as thousands of Afghan refugees, has been underway since the day before Taliban forces captured Kabul on August 15.
The US, UK, and other foreign forces have been racing to carry out airlifts before militaries are set to fully withdraw from the country.
The US and UK have vowed the evacuation missions would continue right down to the wire, with only days to go.
However earlier this week British ministers warned the UK would not be able to help everyone hopeful of being evacuated in time.
