As the US and Taliban negotiate peace, Isis sees a chance to sow fresh chaos in Kabul. Even by the bloody standards of Afghanistan, it was a brutal attack: a suicide bomber at a wedding celebration, detonating his device as children danced and the happy couple completed their marriage rituals. In an instant more than 80 of the 1,000 guests were dead, hundreds injured.

Earlier in July, Donald Trump said “it’s ridiculous” that US troops were still in the country, and Washington is now close to a deal with the Taliban, the reactionary Islamist movement ousted from power by a US-led invasion in the aftermath of the September 11 attacks in 2001.

The agreement would see the 14,000 remaining US forces in Afghanistan withdraw in return for a Taliban commitment to a ceasefire and a pledge not to support acts of international terrorism. However, the Taliban quickly denied involvement, condemned the bombing and termed it “forbidden and unjustifiable,” while indulging in verbal sparring with President Ashraf Ghani, who tweeted that the Taliban “cannot absolve themselves of blame, for they provide platform for terrorists.” In response, a Taliban spokesman alleged that foreign “aggressors” and “the puppet Afghan regime” paved the way for such incidents.

Few events are so joyous and optimistic as a wedding. So why would a terrorist group – even one as brutal as Islamic State, which has claimed responsibility. One reason is that Isis does not believe that restraint serves its purposes. As the atrocities that accompanied its expansion and rule in Iraq and Syria made clear, the group does not aim to win ordinary people’s loyalty but to rule through fear and a few select powerbrokers. Its explicit savagery is not a byproduct of broader strategy.

It is the strategy. But strategies – even those of groups like Isis – do not evolve in a vacuum. There have been significant changes in the political situation in Afghanistan over recent months. Afghan Shiites, who are almost all from the Hazara ethnic group, have suffered discrimination and persecution in the past. Targeted attacks against the Hazara Shiites have in recent years sparked big protests by the community and brought the beleaguered Afghan government under pressure to improve security.

This could happen again and cause unrest, with political ramifications. A few days before the Kabul suicide bombing, an explosion at a Taliban-run mosque and madrasa near Quetta in Pakistan had already cast a shadow over the future of the Taliban-US peace talks, even though the year-long negotiations have entered their final phase. The remote-controlled blast during Friday prayers in Kuchlak killed the mosque’s prayer leader, Hafiz Ahmadullah, the brother of Taliban supreme leader Haibatullah Akhundzada.

Questions were raised about whether peace in Afghanistan would ever be achievable, and whether Daesh could be defeated following a peace deal with the Taliban. The aim was slightly different though. A civil war is already under way, and there is no need to provoke a fresh one. Instead, the attack on the wedding underlined the inability of the Afghan government to protect its own citizens, prompting fear and anger and helping to ensure that any efforts to stabilise the country come to nothing. That militant attacks increase whenever the peace process makes progress is nothing new.

Such attacks ought to strengthen the resolve of the stakeholders to renew their commitment to the cause of peace, especially as there is a real possibility, for the first time since 2001, that the conflict in Afghanistan might end. If the Taliban stop fighting the US and the Afghan government, Isis will aim to take over the role of the main opposition force in the country, gathering to its banners all the malcontents and rejectionists any deal would inevitably create. They would also seek to attract the support of the Taliban’s erstwhile supporters, inside and outside Afghanistan.