to seize the initiative to destroy guerrilla and organized enemy forces. This phase would end when the enemy had been worn down, thrown on the defensive, and driven back from major populated areas. Phase 3. If the enemy persisted, a period of twelve to eighteen months following Phase 2 would be required for the final destruction of enemy forces remaining in remote base areas. The plan was approved by Johnson and marked a profound departure from the previous administration's insistence that the government of South Vietnam was responsible for defeating the guerrillas. Westmoreland predicted victory by the end of 1967. Johnson did not, however, communicate this change in strategy to the media. Instead he emphasized continuity. The change in U.S. policy depended on matching the North Vietnamese and the Viet Cong in a contest of attrition and morale. The opponents were locked in a cycle of escalation. The idea that the government of South Vietnam could manage its own affairs was shelved. Westmoreland and McNamara furthermore touted the body count system for gauging victory, a metric that would later prove to be flawed. The American buildup transformed the South Vietnamese economy and had a profound effect on society. South Vietnam was inundated with manufactured goods. Stanley Karnow noted that "the main PX [Post Exchange], located in the Saigon suburb of Cholon, was only slightly smaller than the New York Bloomingdale's..." Washington encouraged its SEATO allies to contribute troops. Australia, New Zealand, Thailand and the Philippines all agreed to send troops. South Korea would later ask to join the Many Flags program in return for economic compensation. Major allies, however, notably NATO nations Canada and the United Kingdom, declined Washington's troop requests. The U.S. and its allies mounted complex search and destroy operations, designed to find enemy forces, destroy them, and then withdraw, typically using war helicopters. In November 1965, the U.S. engaged in its first major battle with the PAVN, the Battle of Ia Drang. The operation was the first large scale helicopter air assault by the U.S., and first to employ Boeing B-52 Stratofortress strategic bombers in a tactical support role. These tactics continued in 1966–1967 with operations such as Masher, Thayer, Attleboro, Cedar Falls and Junction City. However, the PAVN/VC insurgents remained elusive and demonstrated great tactical flexibility. By 1967, the war had generated large-scale internal refugees, numbering nearly 2.1 million in South Vietnam, with 125,000 people evacuated