As the time approached in 1987 for the renegotiation of the existing base agreement, which had entered into force in 1983 for a five-year period, pressures mounted for a reduction of the United States military presence in Spain. Communist political groups and elements of the Spanish Socialist Workers' Party (PSOE) had campaigned against the bases. Moreover, the base agreement had become a symbol of United States cooperation with Francoist Spain. It was important to many Spaniards to eliminate vestiges of this history by converting Spain's long-standing bilateral relations with the United States into a multilateral undertaking through NATO.