The anxiety gripping Seoul is palpable. Under US pressure, South Korea signed a US$350 billion investment deal last November for a 10-percentage-point tariff reduction, billing it as a strategic alliance. Barely a year on, the facade has crumbled. Last month, US President Donald Trump announced a US$200 billion tranche of the deal with no South Korean official present. Blindsided, Seoul restated its “commercial viability” clause. Trump’s response was blunt.