The US-led NATO forces and the Afghan military forged an unprecedented alliance last month to pull an exceptionally surprising victory. The coalition troops teamed up with the Taliban to quell the rise of the Islamic State (IS) Khorasan in Nangarhar, the far-eastern corner of Afghanistan bordering Pakistan, where the militia-controlled large swaths of countryside. The concerted military offensive resulted in an almost total collapse there of the IS(K). Taliban tightened the noose on IS hideouts by choking their supply routes for weeks while the coalition air support contained its fighters’ movement and the advent of fresh reinforcements. The offensive also forced over 500 Islamic State affiliates, many of them foreigners, to surrender while the remaining making their escape good.

On Wednesday, US Special Representative  Zalmay Khalilzad publically endorsed the covert alliance in a tweet by acknowledging the Taliban’s role in recent advances against the Islamic State in eastern Afghanistan. “The recent campaign in Nangarhar is one example. Effective operations by US/Coalition & Afghan security forces, as well as the Taliban, led to ISIS-K losing territory & fighters. Hundreds surrendered,” tweeted the White House’s special envoy.

The Khorasan chapter, one of Islamic State’s most dreaded affiliates, first popped up in eastern Afghanistan in 2014, when dozens of Pakistani Taliban deserted there new commander after Hakimullah Mehsud was killed in a US drone strike in 2013.

A substantial decline in Taliban-led attacks across Afghanistan has been witnessed since President Trump’s announcement to call off the peace talks. Washington did not ink the peace deal because the militia refused to seize its attacks as a confidence-building measure. Both are adopting a more reconciliatory attitude and the talks are again back on track.

The coalition and Afghan forces have long been battling the IS tooth and nail, including dropping the “Mother of all Bombs” on an IS hideout in Nangarhar but in vain. The tables turned on the militia when the coalition forces joined hands with the Taliban. The IS commanders were already predicting that in case of any peace deal with the US and the Afghan government, the disgruntled adherents of the Islamic Emirate will flock its ranks.

“We are quite confident that a peace deal will prove beneficial for us in terms of gaining manpower and funds. Taliban field commanders and fighters won’t agree on it. They will not cope with the idea of a power-sharing formula. They have been fighting for years to establish an utterly pure Islamic emirate in Afghanistan. Anything less will push them to join our ranks. Dissatisfaction among Taliban field commanders has already emerged and we are aware of it,” said an IS(K) commander in August in a telegram chat.

For Taliban leadership, elimination of Daesh was a strategic imperative, no matter whom they sided with. If not eliminated before striking any deal with Washington and Kabul, the IS could have provided the opportunity to the hardline elements within Taliban to switch sides. Besides religious radicalism and discontent with the likely deal, the need to seek refuge for avoiding local tribal retribution could have also driven the hardliner in the Taliban to join IS(K). The central Taliban leadership still fears that field commanders, especially those on the frontline, may reject the peace deal with the very forces they had been fighting against for the last 18 years.

The extraordinary offensive notwithstanding, it still not certain if the IS has been weakened effectively if not eliminated fully in eastern Afghanistan. As much as Washington and Kabul seem ready to sign the peace accord, the Taliban’s internal dynamics can delay if not scuttle the process. To silence the taunt of surrender, the Afghan militia will need to show off more than a peace accord that paves the way for its mainstreaming in the political process.