The U.S. is one of the few countries in the world that delivers its food assistance mainly via transoceanic shipments of commodity-based in-kind food. This approach is more costly and less timely than cash-based assistance, which includes cash transfers, food vouchers, and local and regional procurement, where food is bought in or nearby the recipient country. The U.S.’s approach is exacerbated by a requirement that half of its transoceanic food shipments need to be sent on U.S.-flag vessels. Assuming that all cash-based assistance has the same cost and timeliness characteristics as local and regional procurement, we estimate the effect of these U.S. food assistance distribution policies on child mortality in sub-Saharan Africa by formulating and optimizing a supply chain model where monthly orders of transoceanic shipments and cash-based interventions are chosen to minimize child mortality subject to an annual budget constraint and to policy constraints on the allowable proportions of cash-based interventions and non-US-flag shipments; by varying the restrictiveness of these policy constraints, we assess the impact of possible changes in U.S. food aid policies on child mortality. The model includes an existing regression model that uses household survey data and geospatial data to forecast the mean mid-upper-arm circumference Z scores among children in a community, and allows food assistance to increase Z scores, and Z scores to influence mortality rates. We find that cash-based interventions are a much more powerful policy lever than the U.S.-flag vessel requirement: switching entirely to cash-based interventions reduces child mortality from 4.4% to 3.7% (a 16.2% relative reduction), whereas eliminating the U.S.-flag vessel restriction without increasing the use of cash-based interventions generates a relative reduction in child mortality of only 1.1%. The great majority of the gains achieved by cash-based interventions are due to their reduced cost, not their reduced delivery lead times.