Complex sentence: Carlos Escudé is a Yale University trained Argentine political scientist and author who as special advisor to Foreign Minister Guido di Tella during the 1990's, with respect to foreign policy strategy vis-à-vis the Western powers.
Split into simpler sentences: Carlos Escudé is a Yale University trained Argentine political scientist and author, who during the 1990s served as special advisor to Foreign Minister Guido di Tella. As such he focused on the foreign policy strategy vis-à-vis the Western powers.