US Army Sales at Kim Chang-bae’s hardware shop in South Korea rise every year thanks to Camp Humphreys, an enormous US military base he is frightened will close in the wake of the summit between Kim Jong Un and Donald Trump. More than 28,000 US troops are stationed in the South to guard against nuclear-armed North Korea, part of a Seoul-Washington security alliance in place since the Korean war ended with an armistice instead of a peace treaty. But with talks between the North Korean and US leaders in Hanoi just days away, speculation is building that the pair could agree to a treaty in return for denuclearisation measures from Pyongyang — and that the withdrawal of US troops might follow. For South Koreans dependent on US troops to make a living — like Kim Chang-bae — that is a worrisome prospect. “Without the presence of US soldiers, many business, including mine, will lose their main source of income,” said Kim, who sells bolts and screwdrivers to Americans station...