A meeting between US officials and representatives of the Taliban had been set for yesterday in Qatar but Afghan government anger at the fanfare surrounding the opening of a Taliban office in the Gulf state threw preparations into confusion.
The squabble may set the tone for what could be arduous negotiations to end a conflict that has torn at Afghanistan's stability since the US invasion following the September 11, 2001, al Qaeda attacks on US targets.
Asked when the talks would now take place, the source in Doha said "There is nothing scheduled that I am aware of", and confirmed that meant they would not happen yesterday.
The opening of the office was a practical step paving the way for peace talks. However, the official-looking protocol surrounding the event raised angry protests in Kabul that the office would develop into a Taliban government-in-exile. A diplomatic scramble ensued to allay their concerns.
The protocol dispute burst into the open on Wednesday when President Hamid Karzai said his government would not join US talks with the Taliban and would halt negotiations with Washington on a post-2014 troop pact.
US Secretary of State John Kerry spoke with Mr Karzai on Tuesday night and again on Wednesday morning in an effort to defuse the controversy, US and Afghan officials said.
A Taliban flag that had been hoisted at the Taliban office on Tuesday had been taken down and lay on the ground yesterday, although it appeared still attached to a flagpole.
A name plate, inscribed Political Office of the Islamic Emirate of Afghanistan, had been removed from the outside of the building. But a similar plaque fixed on to a wall inside the building was still there yesterday morning, witnesses said.
Asked whether the Taliban office had created any optimism about peace efforts, the source replied: "Optimism and pessimism are irrelevant. The most important thing is we now know the Taliban are ready to talk, and sometimes talk is expensive."
Word of the US-Taliban talks had raised hopes President Karzai's government and the Taliban might enter their first-ever direct negotiations on Afghanistan's future, with Washington acting as a broker and Pakistan as a major outside player.
Pakistan's powerful military played a central role in convincing the Taliban to hold talks with Washington, US and Pakistani officials said, a shift from widely held US views it was obstructing peace in the region.
A prisoner swap is seen as likely to happen as the first confidence-building measure between the two sides, said one Pakistani official, who declined to be named.
But he said there were many likely spoilers in the peace process who would want to maintain the status quo to continue to benefit from the war economy and the present chaotic conditions.
"The opening of a Taliban office and the American readiness to hold talks with the Taliban is a forward movement. What happens next depends on the quality of dialogue and political will of the interlocutors," he said.
Pakistan has been particularly critical of Mr Karzai, seeing him as an obstacle to a peace settlement.
Underlining the importance of the peace process to Washington, the State Department said Mr Kerry would travel to Doha for meetings with senior Qatari officials today and Saturday. However, US officials said he would not meet with Taliban representatives.