US exports increase when foreign demand for dollars:

If foreign demand for dollars falls, the value of the dollar typically weakens against other currencies. This depreciation makes US goods cheaper for foreign buyers, which might increase exports in the short term, but it does not directly indicate a rise in foreign demand for US products, leading to a less favorable outcome for exports.

While an initial rise in foreign demand for dollars may lead to increased exports, a subsequent fall complicates the scenario. This fluctuation could result in uncertainty for foreign buyers, potentially leading to decreased purchasing of US goods, thus not definitively indicating a net increase in exports over time.

If foreign demand for dollars remains the same, there is little incentive or change in the economic dynamics that would encourage an increase in US exports. Without a change in demand, the likelihood of increased export activity remains stagnant, as there is no additional purchasing power or investment flowing into the market.