In this role, he was sent to embassies, first at Berlin (during the 1936 Olympic Games) and soon to Paris, where he spent most of his time; he also served at the embassies at Vichy, Buenos Aires, Rome, Havana (witnessing the Cuban Revolution), and Brussels.
After Trujillo's assassination on May 30, 1961, Rubirosa supported his son as successor and attempted to persuade John F. Kennedy to help his government.