After an invasion by the United States and its allies in 2003, Saddam Hussein's Ba'ath Party was removed from power, and multi-party parliamentary elections were held in 2005. The US presence in Iraq ended in 2011, but the Iraqi insurgency continued and intensified as fighters from the Syrian civil war spilled into the country. Out of the insurgency came a highly destructive group calling itself ISIL, which took large parts of the north and west. It has since been largely defeated. Disputes over the sovereignty of Kurdistan Region continue. A referendum about the full sovereignty of Kurdistan Region was held on 25 September 2017. On 9 December 2017, then-Iraqi Prime Minister Haider al-Abadi declared victory over ISIL after the group lost its territory in Iraq.