as well as targeting the pacification and Vietnamization strategy. In the two-year period following Tet, the PAVN had begun its transformation from a fine light-infantry, limited mobility force into a high-mobile and mechanised combined arms force. By 1970, over 70% of communist troops in the south were northerners, and southern-dominated VC units no longer existed. U.S. domestic controversies The anti-war movement was gaining strength in the United States. Nixon appealed to the "silent majority" of Americans who he said supported the war without showing it in public. But revelations of the 1968 My Lai Massacre, in which a U.S. Army unit raped and killed civilians, and the 1969 "Green Beret Affair", where eight Special Forces soldiers, including the 5th Special Forces Group Commander, were arrested for the murder of a suspected double agent, provoked national and international outrage. In 1971, the Pentagon Papers were leaked to The New York Times. The top-secret history of U.S. involvement in Vietnam, commissioned by the Department of Defense, detailed a long series of public deceptions on the part of the U.S. government. The Supreme Court ruled that its publication was legal. Collapsing U.S. morale Following the Tet Offensive and the decreasing support among the U.S. public for the war, U.S. forces began a period of morale collapse, disillusionment and disobedience. At home, desertion rates quadrupled from 1966 levels. Among the enlisted, only 2.5% chose infantry combat positions in 1969–1970. ROTC enrollment decreased from 191,749 in 1966 to 72,459 by 1971, and reached an all-time low of 33,220 in 1974, depriving U.S. forces of much-needed military leadership. Open refusal to engage in patrols or carry out orders and disobedience began to emerge during this period, with one notable case of an entire company refusing orders to engage or carry out operations. Unit cohesion began to dissipate and focused on minimising contact with Viet Cong and PAVN. A practice known as "sand-bagging" started occurring, where units ordered to go on patrol would go into the country-side, find a site out of view from superiors and rest while radioing in false coordinates and unit reports. Drug usage increased rapidly among U.S. forces during this period, as 30% of U.S. troops regularly used marijuana, while a House subcommittee found 10–15% of U.S. troops in Vietnam regularly used high-grade heroin. From 1969 on, search-and-destroy operations became referred to as "search and evade" or "search and avoid" operations, falsifying battle