A civilian helicopter crashed at a NATO base in southern Afghanistan on Sunday, killing 16 people and wounding five others. There was no enemy involvement in the crash, which took place as the helicopter was taking off, a NATO spokesman said. The Mi-8 helicopter, which was operated by a Russian firm, was carrying 17 passengers and three crew, according to Russia's Interfax news agency. The nationalities of those killed have not been revealed. It was the second time a Soviet-era helicopter crashed in a week; on Tuesday, six Ukrainian crew members were killed when an Mi-26 transport helicopter crashed in Helmand. The accident raised the death toll in the multi-national effort to eradicate the Taliban, adding to pressure on Washington and London. July has become the deadliest month of the 8-year-old war in Afghanistan for foreign troops.