Kabul and London (CNN) The marriage contract had just been signed, and the festivities were in full swing. But just as close relatives of the newlyweds were emerging from an upstairs room to join hundreds of friends and family members at a Kabul wedding hall, an uninvited guest walked forward. What should have been a moment of celebration turned into a scene of unimaginable carnage, as an ISIS suicide bomber blew himself up in front of the band playing in the men's section of the venue.

Officials say at least 63 died -- the bride and groom survived -- but relatives think the death toll may be higher. Violent death is an everyday occurrence in Kabul, but this attack shocked many with its sheer savagery. "Before the blast we were so happy, all our family, relatives and friends were at the hall and we were enjoying the wedding," Basir Jan, a brother of the groom, told CNN. "When the blast happened, I saw dead bodies of my relatives and friends. Eight of my close friends were killed in the blast. It was a scene I will always remember."

The devastation represents a personal tragedy the families who were targeted in Kabul at the weekend. But it also provided a bloody backdrop to the final stages of peace talks being held now between the Taliban and the United States.

A wedding hall is devastated after a suicide bomber targeted a ceremony in Kabul.

The US top negotiator, Special Representative Zalmay Khalilzad, tweeted shortly after the bomber walked into the celebration: "We must accelerate the #AfghanPeaceProcess including intra-Afghan negotiations. Success here will put Afghans in a much stronger position to defeat ISIS."

It's a tweet that manages to be both startlingly opportunistic, flawed but largely accurate at the same time. Accurate, since a peace deal between the US and Taliban would enable both to focus on ISIS -- a comparatively tiny, yet brutal part of the insurgency raging in Afghanistan now. Flawed, because a peace deal would not guarantee the Taliban didn't pursue its main enemy, the Afghan government first, before getting around to ISIS. Opportunistic, as the tweet also exposed the "deal at all costs" attitude behind the talks now: The massacre is a reflection of how badly Afghanistan has collapsed, not of how well the proposed peace deal might fix it. Trump wants out of Afghanistan, that much is clear, despite saying last year he would win. But how much of an inglorious an end to America's longest war is he prepared to countenance to make that happen?

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