Chief of Army Staff, General Ashfaq Pervez Kayani Saturday left on an official visit to United States.He is visiting USA on the special invitation of the US Centcom General David Petraeus.During the visit, COAS would meet senior military and government officials at Tampa and Washington. He will also participate in Pakistan-US strategic dialogue. The Chief of Army Staff was seen off at Lahore Airport by Acting Corps Commander and other senior military officials.