The African Union Mission in Sudan (AMIS) was an African Union (AU) peacekeeping force operating primarily in the country's western region of Darfur to perform peacekeeping operations related to the Darfur conflict. It was founded in 2004, with a force of 150 troops. By mid-2005, its numbers were increased to about 7,000. Under United Nations Security Council Resolution 1564, AMIS was to "closely and continuously liaise and coordinate ... at all levels" its work with the United Nations Mission in Sudan (UNMIS). AMIS was the only external military force in Sudan's Darfur region until UNAMID was established. It was not able to effectively contain the violence in Darfur. A more sizable, better equipped UN peacekeeping force was originally proposed for September 2006, but due to Sudanese government opposition, it was not implemented at that time. AMIS' mandate was extended repeatedly throughout 2006, while the situation in Darfur continued to escalate, until AMIS was replaced by UNAMID on December 31, 2007.