Theory predicts that higher trade policy uncertainty (TPU) makes firms delay costly trade decisions, and that rises in uncertainty matter more than falls. This study tests whether rises and falls in US TPU have effects of different size on real US imports from Bangladesh, measured in US customs data and deflated by an import price index. It estimates a nonlinear autoregressive distributed lag (NARDL) model on 253 monthly observations from 2005:07 to 2026:07, with log TPU split into partial sums of increases and decreases and US industrial production as the demand proxy. Bounds tests find a long-run level relationship, but TPU’s long-run effects are small. A 1% rise in TPU lowers real imports by an insignificant 0.035%. A 1% fall raises them by 0.075%, significant only at the 10% level with conventional standard errors. Long-run symmetry is rejected in the main model (p < 0.001) but not once a linear trend is added (p = 0.632), and short-run symmetry is not rejected. The data do not establish an asymmetric effect, and the larger point estimate is for falls in TPU rather than rises. NARDL studies of a trending uncertainty index should test long-run asymmetry with and without a trend.