Strategic thinking under the Eisenhower administration and Secretary of State John Foster Dulles was that of massive retaliation in the face of the Soviet Union's nuclear arsenal.[5] Flexible response was a defense strategy first implemented by President John F. Kennedy in 1961 to address the administration's skepticism of the policy of massive retaliation in the face of strike options limited to total war during the Cuban Missile Crisis.Additionally, much early Cold War strategic asset construction was above-ground soft targets or minimally-hardened such as airfields, pre-nuclear command and control installations, defensive infrastructure, and even ICBM bases.[9] A feature of strategic nuclear weapons, especially in the transcontinental nature of the Cold War, with continent-spanning superpowers that are oceans apart, is the greater range of their delivery apparatus, such as ICBMs, giving them the ability to threaten the enemy's command and control structure and national infrastructure even though they were based many thousands of miles away in friendly territory.Specifically, on the Korean Peninsula, with a nuclear-armed North Korea facing off against an NPT-compliant South Korea there have been calls to request a return of US-owned short range low yield nuclear weapons, nomenclatured as tactical by the US military, to provide a local strategic deterrent to the North's growing domestically produced nuclear arsenal and delivery systems.