MEXICO CITY, Sept. 7 (Xinhua) -- U.S. military hegemony is humanity's "biggest enemy" and prevents countries from exercising their sovereignty, according to an expert. Jaime Tamayo, a political scientist from the University of Guadalajara, told Xinhua in an interview that this hegemony and the actions resulting from it put humanity at risk by keeping the threat of a new war always latent. "It is essential to be clear about who the enemy is," Tamayo stressed, considering that the United States