The ground has been prepared for years for talks with the Taliban. There have been many false starts, many promised talks that never happened.
But their announcement today still dropped like a hand grenade amid the carefully choreographed ceremony "handing over" control of Afghanistan to its national army and police.
That event was full of the happy talk of foreign armies reversing out of a wrong turning they'd been in for too long.
The Taliban announcement - and its confirmation by US officials within minutes - was a sober reminder that happy times are not guaranteed in Afghanistan; that the future of the country is still very much up for grabs.
To see the black turbaned men of the Taliban laying out their programme in English in a setting they called the "Office of the Islamic Emirate of Afghanistan" (their former name for the country) was stunning.
The Taliban announced it today because they want to set the agenda, not have it set by their enemy President Karzai and his foreign allies at a "handover" ceremony.
They are announcing their intention to be part of an Afghan political future, perhaps even to fight in next year's Presidential election, which Karzai cannot take part in.
The reason for their existence in recent years has been to fight foreign "occupiers". Now that the occupiers are clearly leaving, the Taliban need a new reason to be relevant. Otherwise, they might melt away, as they did in 2001 after the initial invasion, when they were driven from power.
Today, on the day foreign troops relinquished their final control of security, the Taliban were announcing their new role, their new goals in the country.
And those remain, at their core, the same; power in order to bring Islamic law and rule to Afghanistan.
Many of the women of the country will shudder tonight. The return of the Taliban threatens to reverse many of the gains in social affairs the West had achieved.
The Taliban will be part of the new Afghanistan; of that there is no doubt.
Today was the start of their Western-recognised comeback.