 Following the Nazi invasion of Russia which cut off their supply of wolfram (tungsten) from Asia, Germany initiated tactics to extract wolfram from Portugal, initially by artificially running up prices in an attempt to get the people to bypass the Portuguese government and sell directly to German Agents.Salazar's government attempted to limit this and in October 1941 Germany retaliated by sinking a Portuguese merchant ship, the first neutral ship to be attacked during World War II.Germany torpedoed a second Portuguese ship in December.