From the German capture of Denmark and Norway, the Swedish overseas trade during World War II was mainly blocked by the battle of the Atlantic, but Swedish diplomats convinced Germany and the United Kingdom to let through a few vessels, mainly to the United States until their entrance into the war, and neutral countries in Latin America. These transports, called lejdtrafiken, "the safe conduct traffic", were monitored by both powers, and ten of them were sunk during the war. Sweden mainly imported petroleum products and agricultural produce, and exported wood products. Overall, petrol imports to Sweden greatly decreased, and substitute fuels were found.
Sweden traded considerable goods with Germany during the war, particularly iron, iron products, ball bearings, and trucks. Sweden attempted to purchase planes from the USA, but these were prohibited by the US government in 1940. Sweden bought 200 planes from Italy instead. As the war progressed, strategic products such as rubber and metals were prohibited.
Some trade was also done using blockade runners like HMS Gay Viking.