President Vladimir Putin on Monday lifted a ban on Russian firms from working on Iranian enrichment sites as he traveled to Tehran for his first visit since 2007. A decree Putin signed today enables Russian firms to work with Iranian companies on the Fordo enrichment site and help Tehran in redesigning its Arak nuclear reactor. Russian companies can now also carry out activities linked to Iranian exports of enriched uranium of more than 300 kilograms in exchange for the supplies of natural uranium to Iran, the Kremlin decree said. Under a historic July deal with world powers, Iran agreed to dramatically scale back its nuclear programme, making it much more difficult for it to develop nuclear weapons.