In April 1967, the civil rights leader Martin Luther King Jr. came out against the Vietnam War with a speech in New York denouncing the "immoral war" whose burden he charged fall disproportionately heavily on black men who more likely to be drafted to fight in Vietnam. King's speech increased the sense of siege in the White House, and hence Rostow's influence. In July 1967, allegations of police brutality led to race riots in Detroit and Newark. In response to the race riots, conservative Republicans and Democrats accused the Johnson administration's civil rights reforms as being the root reason for the riots. Johnson ordered Rostow to collect "such evidence as there is on external involvement in the violent radical community of the Negro community in the U.S". Johnson was apparently hoping that Rostow would find evidence that the Soviet Union and/or China were behind the riots in Detroit and Newark, but his national security adviser was unable to produce any such evidence. The fact that Rostow was ordered to investigate an essentially domestic matter showed that the president thought very highly of him. As the anti-war protests increased, Rostow was able to reassure Johnson that history will vindicate him, leading the president to remark he was "a man of conviction who doesn't try to play president".