Kabul

In 2011, Mike Mullen, then top US military officer, had told the Congress that the Haqqani network was a "veritable arm" of the ISI, Pakistan's main intelligence service, NBC reported. The Taliban group was never designated by the US government as a terrorist organisation, but the Haqqani network, which has close ties to al-Qaeda and Pakistani intelligence, has long held that distinction.

There is growing concern among the western allies that Islamist terrorists may have successfully infiltrated the thousands of Afghans and other foreigners, and some of them may have actually boarded planes for Europe and the US. The concern is sourced from Pentagon, and no less than US President Joe Biden remarked on Sunday that "terrorists may seek to exploit the situation and target innocent Afghans or American troops".

"I drove a group of people to the airport early morning. We failed to reach the airport as Taliban soldiers did not allow vehicles to approach the airport, I drove them back to their home," a cab driver Mohammad Quraishi told Xinhua news agency. On Thursday evening, a suicide bombing rocked a gate of the airport where a crashing crowd was waiting for evacuation flights, and later another explosion hit the nearby Baron Camp, a former coalition base.

A Taliban official says at least 28 of the Afghans killed were Taliban members. Evacuation of civilians have now been accelerated after the attacks, a Western security official told a global news wire, adding that flights are taking off regularly US President Joe Biden has sworn revenge on the attackers, saying he would "hunt them down". This, as the US warned that more attacks could come, with US commanders saying they were on alert for possible rockets or vehicle-borne bombs targeting the airport, BBC said.

"He condemns this terrorist attack which killed and injured a number of civilians, and extends his deep condolences to the families of those killed. He stands in solidarity and wishes a speedy recovery to those injured," Dujarric said on Thursday, Xinhua news agency reported. "This incident underscores the volatility of the situation on the ground in Afghanistan but also strengthens our resolve as we continue to deliver urgent assistance across the country in support of the Afghan people," the spokesman added.

The number of US service members killed in the attacks has risen to 13, with 18 more injured troops currently in the process of being flown out of the country, according to the latest update by Bill Urban, public affairs officer of the US Central Command. The blast at the airport was followed by another one at the adjacent Baron Hotel, whose details are being figured out by the US military.

"I want to stress that this threat of a terrorist attack is one of the constraints that we've been operating under in Operation Pitting, in the big extraction that's been going on, and we've been ready for it; we've been prepared for it," Johnson told the reporters after an emergency meeting, Xinhua reported.

"We can confirm that a number of US service members were killed in today's complex attack at Kabul airport. A number of others are being treated for wounds. We also know that a number of Afghans fell victim to this heinous attack. "Our thoughts and prayers go out to the loved ones and teammates of all those killed and injured," Pentagon Press Secretary John Kirby said in a statement.

"We can confirm an explosion outside the Kabul airport. Casualties are unclear at this time. We will provide additional details when we can," Pentagon Press Secretary John Kirby said in a tweet. However, a Taliban leader said that at least 11 people, including women and children, were killed, and a number of Taliban guards got injured in the blast.

"It was not a surprise that Kabul fell, but we did not consider the speed at which it happened to be probable. We made our assessments on the intelligence basis, but it has turned out that our assessment was simply too optimistic," Xinhua news agency quoted Svend Larsen, acting head of the FE, as saying in a statement issued on Wednesday.