Operation Unified Assistance is the name of the United States military's response to the 2004 Indian Ocean tsunami.On 28 December, the first elements of the Combined Support Force (CSF-536) were deployed to Utapao, Thailand following that country's approval of the use of that base.More than 12,600 Department of Defense personnel were involved in the relief effort.The United States offered assistance from its troops stationed in Japan.The United States military participated in the Combined Coordination Center.