US President Joe Biden says a new terror attack in Afghanistan is highly likely in next 24-36 hours as the Taliban close in on controlling Kabul airport.
The leader issued the warning as the final UK evacuation flight solely carrying civilians from Afghanistan left the airport on Saturday.
Meanwhile the US military is rushing to complete its final evacuation in time for the August 31 deadline by the Taliban to withdraw troops.
On Thursday 13 US troops were among as 170 people, including three Brits, who were killed when an ISIS-K suicide bomber targeted the airport.
In a statement warning about a possible terror attack, the President said: "This morning, I met with my national security team in Washington and my commanders in the field.
"We discussed the strike that US forces took last night against the terrorist group ISIS-K in Afghanistan.
"I said we would go after the group responsible for the attack on our troops and innocent civilians in Kabul, and we have.
"This strike was not the last.
"We will continue to hunt down any person involved in that heinous attack and make them pay.
"Whenever anyone seeks to harm the United States or attack our troops, we will respond. That will never be in doubt."
He continued: "The situation on the ground continues to be extremely dangerous, and the threat of terrorist attacks on the airport remains high.
"Our commanders informed me that an attack is highly likely in the next 24-36 hours."
Paying tribute to the US troops who were killed he added: "The 13 service members that we lost were heroes who made the ultimate sacrifice in service of our highest American ideals and while saving the lives of others."
The Taliban has issued a warning that if troops had not left by August 31 "there will be consequences".
The Pentagon has insisted that some gates at the airport remain open until then and US passport holders can still get in.
But the US Embassy warned citizens on Saturday to not to approach the airport and avoid airport gates in an alert.
Taliban authorities have already ordered Afghan nationals to stop travelling to Kabul's airport.
It has sealed off access to the airport on Saturday to most Afghans hoping to leave which means only those who are inside the site have a chance of fleeing Afghanistan.
Zabihullah Mujahid, the Taliban's main spokesman, said they were holding some positions within the airport to "peacefully take control" once the US troops have left.
UK Defence Secretary Ben Wallace warned that the threat from terror groups will only "grow the closer we get to leaving" following the suicide bomb attack.
