Complex sentence: Sáenz Garza served as Secretary of Foreign Affairs during Calles'time as President and continuously defended the Calles Administration's decision to cut oil to the United States when US Secretary of State Frank Kellog tried to bargain for a deal.
Split into simpler sentences: Sáenz Garza served as Secretary of Foreign Affairs during Calles'time as President. During his tenure, he continuously defended the Calles Administration's decision to cut oil to the United States when US Secretary of State Frank Kellog tried to bargain for a deal.