For most of the twentieth century the Swedish Navy focused on the threat of a full-scale invasion of Sweden via the Baltic and on protecting commercial shipping. Sweden's location on the Scandinavian peninsula makes it highly dependent of maritime trade: 90% imports and exports enter or leave Sweden through the Baltic. In 1972 the government decreed that non-military measures should be used to protect merchant shipping. The resolution led to the de-commissioning of all the navy's destroyers and frigates, though the non-military measures the government intended to use to protect shipping have never been specified.