An Afghan man reads news of a second round in presidential elections
By Martin Patience
BBC News, Kabul
It was a decision that Western leaders had waited to hear for days. At the presidential palace, the Afghan leader, Hamid Karzai, finally accepted that he had failed to win an outright majority, and that this election requires a second round.
It was no coincidence that a host of ambassadors and the UN special envoy, Kai Eide, were in attendance.
The man who did most to end the political deadlock, US senator John Kerry, stood alongside President Karzai during the announcement.
The Afghan leader has been the subject of a fevered round of diplomacy, receiving phone calls from world leaders urging him to accept a second round.
President Karzai believed - and perhaps still does - that an election victory had been stolen from him.
But his position was weakened by the publication of report by a UN-backed panel on Monday, which showed that a third of the incumbent's votes were fraudulent.
That meant that President Karzai's share of the vote had dropped below the 50% mark, meaning a second round was constitutionally required.
Two option scenario?
Mr Karzai had known the report's findings since last week.
And finally on Tuesday, he caved in to the overwhelming international pressure to accept this.
What will happen next is still not clear: there appear to be two options.
The first is that President Karzai and his challenger Dr Abdullah Abdullah could agree to form a national unity government.
Insurgents will be determined to disrupt a second round of voting through attacks or intimidation, something they did successfully during the first round
But it is not clear what form any government would take - and negotiations could drag on for weeks, if not months.
And any power-sharing deal may produce a weak administration, at a time that Afghans and the West want decisive leadership from the government.
The second option, a run-off, is still a strong possibility. It is scheduled in two weeks' time because of the onset of the harsh Afghan winter, which makes many parts of the country inaccessible.
Western officials say they have been planning for this eventuality for months but to hold a successful second round will be a huge challenge.
Ballots will need to be distributed across the country and election workers hired.
The role of the Independent Election Commission, which organises the ballot, will also come under fierce scrutiny. It was appointed by President Karzai and is regarded as biased towards the incumbent.
Then there is the security situation. Insurgents will be determined to disrupt a second round of voting through attacks or intimidation, something they did successfully during the first round.
Could a second round be regarded as credible if voter turn-out was extremely low?
And finally there is the all-important issue of fraud. There will be no guarantee that there will not be massive fraud a second time around.
While the deadlock may have been broken for now, there could be fresh political crises before this election - which was meant to help stabilise Afghanistan - finally comes to end.