 Vann's reports criticizing Diệm's regime as corrupt and incompetent were most unwelcome to McNamara who contended that the reforms advocated by Vann were unnecessary.In March 1963, Vann resigned from the Army as he was informed that his career was over.After the Battle of Ap Bac, a debate began in the Kennedy cabinet about the viability of the Diệm regime, which was reinforced by the Buddhist crisis, which began in May 1963.