A Korean Peninsula outside the defense perimeter of the United States, without the shield of the American nuclear umbrella, and with no U.S. ground troop presence, sounds like the cherished dream of North Korean leader Kim Jong Un. Yet, if his words are to be believed, this is the prescription for the future of not only South Korea but of Japan, as envisioned by Republican presidential candidate Donald Trump.

America has gone down this path before on at least two previous occasions. Early in 1950 then Secretary of State Dean Acheson delivered an address where he stated that “The defensive