In the early 20th century, Serbia was economically a satellite of the Habsburgs, its major export being pork, most of which was bought by Austria-Hungary.
Specifically, in an attempt to reduce its economic dependence on Austria-Hungary, Serbia began to import French, rather than Austro-Hungarian, munitions and established a commercial treaty with Germany in 1904 and a customs union with Bulgaria in 1905 that ended the sale of tariff-laden Austrian goods in Serbia.
[1]: 23 Long used to setting economic policy, Austria-Hungary responded in April 1906 by closing its borders to Serbian pork.
Serbia refused to bow to Vienna, gained French investment to build new packing plants for international trade, began to order materials from the Austro-Hungarian rival Germany and pressured the Austrian-administered provinces of Bosnia and Herzegovina for a trade outlet on the Adriatic Sea.
[1] That caused Austria-Hungary to concede the conflict by March 1908, as can be shown by the trade statistics of the period in question:[2]