Workers prepare an MQ-1C Gray Eagle unmanned aerial vehicle for static display at Michael Army Airfield, Dugway Proving Ground in Utah in this US Army handout photo

Workers prepare an MQ-1C Gray Eagle unmanned aerial vehicle for static display at Michael Army Airfield, Dugway Proving Ground in Utah in this US Army handout photo

Workers prepare an MQ-1C Gray Eagle drone at Michael Army Airfield, Dugway Proving Ground in Utah September 15, 2011. Reuters/U.S. Army/Spc. Latoya Wiggins/Handout

March 15, 2017 1:00 PM (UTC+8)