NATO member Turkey refused to allow its territory to be used by the US Army's 4th Infantry Division for the invasion. As a result, the SAD, US Army Special Forces joint teams and the Kurdish Peshmerga were the entire northern force against Saddam's Army during the invasion. Their efforts kept the 1st and 5th Corps of the Iraqi Army in place to defend against the Kurds rather than their moving to contest the coalition force coming from the south.