For the record.
Summation: The strategy of the US is founded not on geographical defense but rather on protecting and extending "Enlightenment values," that is, liberalism.
Ladies and gentlemen, we have no room for complacency, and history makes clear that America has no preordained right to victory on the battlefield. Simply, we must be the best if the values that grew out of the Enlightenment are to survive....Under Christendom it was "saving souls."
United States Department of Defense
Remarks by James Mattis on the National Defense Strategy
James Mattis | US Secretary of Defense
Delivered on January 19, 2018