The conference today was a one-day event, hosted by the Netherlands, to rally the world to Afghanistan's side. 70 country leaders attended, even Iran:
BBC: The presence of Iran's deputy foreign minister, Mohammad Mehdi Akhoondzadeh, has been applauded by the US.
"Iran is fully prepared to participate in the projects aimed at combating drug trafficking and the plans in line with developing and reconstructing Afghanistan," he said, according to AFP news agency.
But earlier, he said Afghans held the key to the future of their nation, not the international troops fighting the Taleban.
"The presence of foreign troops can't bring the peace, security and stability to the country," he told Iranian state media.
However, the BBC's international development correspondent, David Loyn, says that behind Iran's routine criticism lays a far more nuanced approach.
Mr Akhoondzadeh said Iran had increased the capacity of the docks at Chabahar - its nearest port to Afghanistan - to allow non-military supplies to travel into Afghanistan via Iranian territory.
Our correspondent says the cautious overture by Iran comes in response to the new mood set by the Obama White House.