BBC News reports the International Atomic Energy Agency says significant progress has been made in its probe into the possible military dimensions of Iran's nuclear program. IAEA director-general Yukiya Amano said Iran had handed over environmental samples from the Parchin military site, which he was able to visit on Sunday. But Amano cautioned that "much work" remained before the investigation could be completed by December's deadline. Western powers suspect that nuclear weapons research took place at Parchin. But Iran has denied this and insists that its nuclear program is entirely peaceful. The completion of the IAEA's investigation is crucial to the implementation of July's comprehensive agreement between six world powers and Iran, under which the country will limit its sensitive nuclear activities in return for the lifting of sanctions.