 Other aerial campaigns (Operation Barrel Roll, Operation Steel Tiger, Operation Tiger Hound, and Operation Commando Hunt) were directed to counter the flow of men and material down the PAVN logistical system that flowed from North Vietnam through southeastern Laos, and into South Vietnam known as the Ho Chi Minh Trail.President Johnson had already appointed General William C. Westmoreland to succeed General Harkins as Commander of MACV in June 1964.Under Westmoreland, the expansion of American troop strength in South Vietnam took place.