During the 1964 and 1968 elections, and the 1967 plebiscite on the political status of Puerto Rico, the MPI promoted a boycott. Throughout the decade the MPI campaigned against the presence of big US corporations denouncing they hindered the island's development, destroyed native industries and agriculture, and exploited the workers. The MPI gathered sympathies among students, workers, intellectuals and poor communities, and advocated civil disobedience and resistance. Opposition amongst the youth and students to compulsory military service in the US Army (in which Puerto Ricans had to serve since 1917); to the presence of the ROTC at the University of Puerto Rico; to aggressive US military policies in the Caribbean, Latin America, Southeast Asia and elsewhere; and to American military installations on the island fueled the activity of the MPI and this in its turn created a perspective of a possible decolonization.