The US aid co-ordinator for Afghanistan has warned that unless donors step up aid efforts, the Taleban will be back.
More funds are needed to tackle a resurgent Taleban, says US
Speaking to the BBC on a visit to London, William Taylor said the international community had to make clear its long-term commitment.
"The Taleban say the Americans have the watches and the Taleban have the time. We have to prove them wrong," he said.
The US is pressing European governments for cash ahead of an Afghan funding conference scheduled for early March.
Washington recently more than doubled its assistance for this year to $1.6bn.
But some European governments say they do not want to be pushed into making new commitments when the US is trying to define the agenda in its election year.
Mr Taylor, the Department of State's special representative for donor assistance to Afghanistan, said that was "a very good reason for the Europeans to step up their contributions so that it is not an American show".
Mr Taylor says the pace of reconstruction must be stepped up
After meeting British officials in London, he expressed confidence other donors would come up with new funds.
The Afghan Government hopes to raise much larger sums of money than the $4.5bn pledged in Tokyo in 2002 shortly after the Taleban were toppled.
The US co-ordinator admitted the Tokyo estimate of Afghanistan's needs had been "done in a hurry" but he was not sure the Afghan Government would get the $15bn to $20bn it may ask for.
One British source said even if the Americans had their own agenda "there was undoubtedly a need to give more money". But some other donors are still reluctant to give the long-term commitment the Afghan Government says its needs.
Mr Taylor also conceded the pace of reconstruction had to be urgently stepped up.
A recent study by the American non-governmental agency, Care, and the Centre on International Co-operation in New York pointed out that only 1% of Afghanistan's reconstruction needs had been met so far, due to donor delays and security concerns.
The outgoing UN envoy for Afghanistan, Lakhdar Brahimi, recently said 5,000 to 10,000 more coalition troops would be needed to make south and south-east Afghanistan safe for the delivery of aid.
Mr Taylor said he believed that figure was "overstating the case".
But he admitted increasing attacks by Taleban forces in that part of Afghanistan demanded a greater international military presence.
He said the demand would now be met by the expansion of small military teams, known as provincial reconstruction teams, or PRTs, a move some aid agencies say is not enough.
He also dismissed growing concern that Afghanistan was not safe enough or ready to hold parliamentary and presidential elections this summer, as called for in the 2001 Bonn accord.
"The message from Afghans is loud and clear," Mr Taylor said.
"Afghans think they were promised, and think they deserve, the right to choose their own leaders."
When asked about concerns that the US call for "acceleration" was linked to the timetable of American elections in November, Mr Taylor said: "We all remember what happened in the United States [on 11 September, 2001] and where those attacks came from.
"That's what motivates us to accelerate our work."