100 points! national security! which of the following distinguishes u. s. national security policy in the late 18th-century from 21st-century national security policy? eighteenth-century national security focused on military defense from threats posed by european armies while 21st-century national security must address non-military threats, including those inside the country’s borders. eighteenth-century national security relied solely on intelligence gathering to prevent an attack; 21st-century national security policies focus on responding to cyberterrorism after an attack takes place. eighteenth-century national security sought to isolate the nation from all threats by limiting travel across our borders; 21st-century national policy seeks to isolate threats by imposing economic barriers on other countries. twenty-first century national security policy is remarkably similar to 18th-century national security policy as there is strong reluctance in washington to change successful programs.