The Johnson Doctrine evolved from activities occurring in the Dominican Republic on April 24, 1965. On this date, a civilian government (headed by Donald Reid Cabral) was attacked by liberal and radical followers of Juan Bosch. By April 28, the military seemed to have the upper hand, but uninformed Washington officials hastily concluded that marines would have to land to prevent a Castro-style revolution.
Faced with the Dominican Revolt, the Johnson administration adopted a view that the uprising was part of a larger challenge to American security everywhere.
On April 30, President Johnson announced that
people trained outside the Dominican Republic are seeking to gain control.
The CIA didn’t agree. Johnson was furious with the CIA’s stance and ordered the FBI to
find me some Communists in the Dominican Republic.
On May 2, 1965, Johnson announced that
The American nations cannot, must not, and will not permit the establishment of another Communist government (like Cuba) in the Western Hemisphere.
President Johnson warned that change “should come through peaceful process” and he pledged that the United States would defend “every free country of this hemisphere.” This announcement became known as the Johnson Doctrine.