The Islamic State group’s affiliate in Afghanistan is poised to develop the capability to launch attacks against the US in as soon as six months, US intelligence agencies believe.

One of the Pentagon’s top civilian officials revealed the assessment at a Senate hearing Tuesday morning, seemingly surprising some members on the dais at a time of widespread scrutiny into whether the Joe Biden administration made the right decision to withdraw fully from its longest war zone, U.S. News reports.

“It’s precisely that threat that we need to remain vigilant, and disrupt,” Colin Kahl, the undersecretary of defence for policy, told the Senate Armed Services Committee on Tuesday morning – the latest hearing into the calamitous U.S. pullout from Afghanistan. “We actually are fairly certain they have the intention to do so.”

Kahl said the terrorist network, known as ISIS-K, ISKP or IS-Khorasan, among others, “could potentially” develop the capability to launch external attacks within six-12 months. Likewise al-Qaida, which maintains safe havens in Afghanistan now under control of its allies the Taliban, “could potentially” have that capability in one-two years, Kahl added, citing U.S. intelligence assessments.

Analysts believe the Islamic State group’s Afghan presence represents perhaps the most potent foreign threat to America.

“Right now, ISIS-K is probably the most capable in terms of orchestrating a plot that could be a viable threat to the U.S. homeland,” Colin Clarke, senior research fellow at private intelligence firm The Soufan Group, tells U.S. News. Other Islamic State group affiliates, including in West Africa and Central Africa, have momentum but are more focused on local issues.

Others believe the threat timeline ISIS-K presents is not unique.

“Al-Qaida is far better positioned with its safe haven in Afghanistan,” says Bill Roggio, senior fellow at the Foundation for Defense of Democracies, who has mapped in detail the terrorist threats in and around Afghanistan. “ISIS-K is fighting for survival against the Taliban and al-Qaida.”

“All al-Qaida and ISIS branches have the potential to plot and execute attacks,” Roggio says. He points out, for example, that the U.S. continues to target al-Qaida attack planners in Syria.

President Joe Biden based his contentious decision to end the U.S. military presence in Afghanistan after 20 years at least in part on the apparent success in crippling al-Qaida after it carried out the Sept. 11 attacks that first launched the war.

“The U.S. did what we went to do in Afghanistan,” Biden said in a press conference in the White House East Room in July to justify his decision. He cited killing al-Qaida leader Osama bin Laden, the supposed degradation of terrorist groups in the country and preventing it from becoming a safe haven to plan attacks against the U.S.

The U.S. diplomatic and intelligence presence in Afghanistan have also withdrawn following the stunning collapse in August of the Western-backed government in Kabul. That fallout has raised questions from Republicans and Democrats alike on Capitol Hill about the extent to which the U.S. can maintain pressure on terrorist groups in a country into which it has limited visibility.

The Pentagon has said consistently since August it maintains the capability to launch counterterror operations in Afghanistan against America’s enemies but has refused to provide more specifics. Analysts, legislators and other critics have since seized upon an errant drone strike in the final days of the emergency U.S. withdrawal that targeted terrorists but accidentally killed an aid worker and other civilians as an example of the new limitations on current counterterror capabilities.

Among the greatest limiting factors is U.S. access to the land-locked country, combined with thorny relations with its neighbours, chiefly Pakistan. The supposed U.S. ally has also maintained strong connections with Taliban networks in the region.

Kahl confirmed recent reporting that the U.S. is currently engaged in talks with Pakistan to maintain its current agreements to use Pakistani airspace to launch attacks against terrorist threats in Afghanistan. It remains unclear the extent to which Islamabad would cooperate with the U.S. and not work secretly to undermine its missions.