The insurgents in Iraq have been composed of a diverse mix of militias, foreign fighters, all-Iraqi units or mixtures opposing the American-led Multi-National Force – Iraq and the post-2003 Iraqi government. During the height of the Iraq War in 2006 to 2008, the fighting involved both armed conflict against the American-led military coalition, as well as sectarian violence among the different ethnic groups within the population. The insurgents were involved in asymmetric warfare and a war of attrition against the American-supported Iraqi government and American forces in central Iraq, while conducting coercive tactics against rivals or other militias. Iraq's deep sectarian divides have been a major dynamic in the insurgency, with support for the insurgents varying among different segments of the population.