According to the Telegraph,
Iran's Revolutionary Guards have taken the extraordinary step of cutting down thousands of trees in Teheran to prevent United Nations inspectors from finding traces of enriched uranium from a top-secret nuclear plant.... According to western intelligence sources, more than 7,000 trees which may have contained incriminating nuclear traces have been lost in a popular parkland area in the city near the Lavizan atomic research centre.... The order to cut down the trees was given by Mohamed Baker Khalibaf, the mayor of Teheran, who is close to President Mahmoud Ahmadnijehad. The official explanation for the destruction of the trees was to create a national park.