In New York, Aguirre took up a post as a lecturer at Columbia University. After the Pact of Madrid between the US and Spain, he went to France, where the Basque government-in-exile was established. There, he found that France's Vichy government had sequestrated the Basque government building and that President Charles de Gaulle was maintaining it on behalf of Francoist Spain. The building is now the Instituto Cervantes.