International studies professor Renato Cruz De Castro said at a Boston University talk on Monday that the Phillipines could not stay out of a war over Taiwan. | By Julian J. Giordano By Claire Y. An and Rory Liu, Contributing Writers The Philippines could not stay out of a war over Taiwan, Renato Cruz De Castro, an international studies professor at De La Salle University, said at Boston University on Monday, arguing that geography has made the country’s alliance with the United States essential.