This is exactly the case of the assassinations of President John F. Kennedy, Civil Rights Leader Martin Luther King Jr. and Presidential Candidate Robert F. Kennedy. All three were marked as threats to the national security of the United States of America because of their efforts to bring an end to the Vietnam War.
President Kennedy had called for the withdrawal of some of the armed forces from Vietnam by the end of 1963 and further the complete withdrawal of all forces by the end of 1964. This call was made a few weeks before his murder.
Martin Luther King Jr. had taken a public stand against the War in Vietnam in 1967 and had called for African-American people to boycott the war by refusing to serve before his April 4, 1968 murder.
Predidential Candidate Robert F. Kennedy had just won the California Presidential Primary on his way to the White House. His solid promise that he would end the Vietnam War when elected President was enough to finish him off the very night of his big win.
It is true that these three men were hated by J. Edgar Hoover as well as Mafia Bosses in the United States and around the world and that the threat to end the war would cut into the income of the Military Industrial Complex, Worldwide Intelligence Services as well as Organized Crime. Billions of dollars were flowing into the bank accounts of these entities because of the Vietnam War and the black market economy it created. American military forces were being used without there knowledge to protect shipments of heroin from Southeast Asia that were bought, sold and used in America. Few people outside of Organized Crime knew the details of the business that maintained this flow of money, weapons and drugs but those who did cooperated in the executions of JFK, MLK and RFK.