On August 4, 1964, as events in the Tonkin Gulf unfold, Secretary of Defense Robert McNamara apprised President Lyndon B. Johnson of the situation in a series of phone calls. In the third secretly recorded phone call of the day, McNamara reports that two U.S. destroyers deployed in the Gulf east of Vietnam are under attack. While McNamara did not know it at the time, the information he relayed was later determined to be false.