National Security Advisor McGeorge Bundy drafts and signs National Security Action Memorandum 328 on behalf of President Lyndon B. Johnson. This document came out of National Security Council meetings that were held on April 1 and April 2. The memorandum authorized U.S. personnel to take the offensive in South Vietnam to secure “enclaves” and to support South Vietnamese operations. The so-called “enclave strategy” called for the U.S. forces to control the densely-populated coastal areas while the South Vietnamese forces moved inland to fight the communists. This memorandum represented a major mission change for the American soldiers and Marines who had recently arrived in Vietnam. American forces had been limited to strictly defensive operations around the U.S. air bases, but the memorandum authorized them to go on the offensive to secure large areas of terrain, an escalation of U.S. involvement in the war.