AlJazeera : The US government is stepping up pressure on Hamid Karzai, the Afghan president, to crack down on corruption.

Analysts say the issue affects every aspect of official life in Afghanistan.

From petty bribes to grand-scale fraud and extortion, corruption is thought to account for billions of disappearing dollars each year - so what can really be done to stop it?

Al Jazeera's Jonah Hull reports from Kabul.