Iran nuclear talks thrown lifeline, but time running short
All sides here in Vienna wanted a deal. The US Secretary of State John Kerry said they would have been fools to walk away without agreeing to keep talking.
In Tehran, President Hassan Rouhani said that "steps forward" had been taken.
In an interview in Iran, he said: "The path of the negotiations will lead to a final agreement, whether it's today or tomorrow."
All sides accept the negotiation is difficult.
But they will keep talking because the alternative could turn out to be war.
Before the initial agreement in Geneva a year ago, the Middle East seemed to be sliding slowly but inexorably into a war over Iran's nuclear plans.
Israel had threatened an attack many times.
The deal they have been discussing in Vienna is complex, but technical details are not the main reason why they need more time to talk.
At the heart of the talks there still is no agreement on the vital equation - the amount of uranium that Iran would be able to enrich, and the extent to which sanctions against it would be lifted.
Before he left for the airport, Britain's Foreign Secretary Philip Hammond told the BBC that they had hoped for more progress.
"Of course it's a disappointment, but rather than continue blindly we have to recognise the reality that we're not going to get to a deal by tonight.
But we have made enough progress to make us confident that we can get to a deal… we will carry on, there will be meetings during December, we will keep the momentum going, and we all focus on resolving the issues that still remain to be resolved."
Progress in the talks about Iran's nuclear programme became possible after Hassan Rouhani was elected President of Iran in the summer of 2013.
He made it clear that he believed that he had a mandate for change.
In his first few months in office President Rouhani smiled his way through a visit to the United Nations General Assembly in New York, and even spoke on the phone to President Barack Obama on his way to the airport.
Working out what is happening in Iran is always difficult. But when President Rouhani took office the consensus seemed to be that he had a licence from Iran's Supreme Leader, Ayatollah Ali Khamenei, to negotiate.
It was not going to last forever.
It seems it will stretch into the next six months, but it will not be renewed indefinitely.
In Tehran opponents of talks argue that the West cannot be trusted in any circumstances, that it will not rest until it destroys the Islamic Republic.
What is doubly dangerous for the talks is that hardliners are circling in Washington DC as well.
From the New Year, Republicans will control both houses of the US Congress.
It is more than possible that the new congress will try to impose more sanctions on Iran.
That would most likely mean an abrupt end to the talks.
A tacit alliance seems to be forming between Saudi Arabia and Israel to torpedo negotiations with Iran.
Both countries have deep suspicions about the Islamic Republic.
For the Saudis, Iran is the rival regional superpower.
And as the negotiators were meeting in Vienna, Israel's Prime Minister Netanyahu once again compared Iran to Nazi Germany.
"No deal is better than a bad deal," he told the BBC.
"The deal that Iran was pushing for was terrible.
"The deal would have left Iran with the ability to enrich uranium for an atom bomb while removing the sanctions.
"The right deal that is needed is to dismantle Iran's capacity to make atomic bombs, and only then dismantle the sanctions. Since that's not in the offing, this result is better."
In the end, a deal might be possible.
All the participants in the talks in Vienna want one.
But the hardest part could be selling it to sceptics - especially in Tehran and Washington DC.