Final answer:
President Kennedy responded to the perceived missile gap by advocating for a policy called Flexible Response, which involved increasing conventional forces to provide more options beyond nuclear retaliation.
Step-by-step explanation:
President Kennedy's response to the perceived "missile gap" between the U.S. and the Soviet Union was to advocate for a policy called Flexible Response.
This approach involved building up conventional forces, particularly Special Forces, to provide the U.S. military with options beyond nuclear retaliation. Kennedy believed that increasing conventional capabilities would provide a more flexible and effective response to any potential threat.