Chief of Army Staff General Ashfaq Pervez Kayani has left for United States to attend the third phase of Pak-US strategic dialogue which would start in Washington from tomorrow. Pakistan Army chief will hold meetings with US military officials and the members of Obama administration during his stay in United States, ISPR spokesman said. The officials of the two countries will consider cooperation in energy, agriculture, education, security and other sectors in the talks that will last for three days.