Republican presidential candidate Donald Trump has alarmed US allies in Asia and elsewhere by suggesting that American military support should depend on their willingness to pay. But he would not be the first US president to consider shaking up time-honored military deployments.
Four decades ago, then-President Jimmy Carter tried to withdraw American troops in South Korea, and failed.
He wanted to trim fat from the US defense budget and put pressure on South Korea over human rights abuses, but hit a wall of opposition in his own administration and in Seoul.
Carter's experience demonstrates the perils of tinkering with alliance commitments. Those commitments may be more urgent today than in Carter's time, given North Korea's growing nuclear arsenal and its progress toward having missiles that could strike the United States.
