There is an enduring consensus about America’s role in the world, which is due to the fact that while administrations may change, fundamental U.S. interests have not. These include protecting the U.S. homeland from catastrophic attack, sustaining a global system marked by open lines of communication to facilitate commerce, and preserving regional balances of power. Far from being a reluctant imperialist or hegemon on the offensive, the United States tends to fill security voids when they are created (even if often late to the game) to ensure the international system remains functional. To be sure, future U.S. grand strategy will be global and multilateral, but it will be much more selective than it is today.
Foreign policy consists in bringing into balance, with a comfortable surplus of power in reserve, the nation’s commitments and the nation’s power. — Walter Lippman.
 Walter Lippmann, U.S. Foreign Policy: Shield of the Republic (Boston, MA: Little, Brown, 1943).