WASHINGTON, Oct. 14 (Xinhua) -- The United States and Greece on Thursday renewed a bilateral defense agreement to enhance their security cooperation. U.S. Secretary of State Antony Blinken and visiting Greek Foreign Minister Nikos Dendias signed an amendment to the U.S.-Greece Mutual Defense Cooperation Agreement (MDCA), which has allowed for U.S. forces to train and operate within Greek territory since 1990.