What was the Balkan policy?

The Russian Active Balkan Policy 1906-1913

Russia's earlier Far Eastern policy required holding Balkan issues in abeyance, a strategy Austria-Hungary also followed between 1897 and 1906. Japan's victory in 1905 had forced Russia to make deals with the British and the Japanese. In 1907 Russia's new foreign minister, Aleksandr Izvol'skiy, concluded agreements with both nations. To maintain its sphere of influence in northern Manchuria and northern Persia, Russia agreed to Japanese ascendancy in southern Manchuria and Korea, and to British ascendancy in southern Persia, Afghanistan, and Tibet. The logic of this policy demanded that Russia and Japan unite to prevent the United States from establishing a base in China by organizing a consortium to develop Chinese railroads. After China's republican revolution of 1911, Russia and Japan recognized each other's spheres of influence in Outer Mongolia. In an extension of this reasoning, Russia traded recognition of German economic interests in the Ottoman Empire and Persia for German recognition of various Russian security interests in the region. Russia also protected its strategic and financial position by entering the informal Triple Entente with Britain and France, without antagonizing Germany.
In spite of these careful measures, after the Russo-Japanese War Russia and Austria-Hungary resumed their Balkan rivalry, focusing on the Kingdom of Serbia and the provinces of Bosnia and Herzegovina, which Austria-Hungary had occupied since 1878. In 1881 Russia secretly had agreed in principle to Austria's future annexation of Bosnia and Herzegovina. But in 1908, Izvol'skiy foolishly consented to support formal annexation in return for Austria's support for revision of the agreement on the neutrality of the Bosporus and Dardanelles--a change that would give Russia special navigational rights of passage. Britain stymied the Russian gambit by blocking the revision, but Austria proceeded with the annexation. Then, backed by German threats of war, Austria-Hungary exposed Russia's weakness by forcing Russia to disavow support for Serbia.
After Austria-Hungary's annexation of Bosnia and Herzegovina, Russia became a major part of the increased tension and conflict in the Balkans. In 1912 Bulgaria, Serbia, Greece, and Montenegro defeated the Ottoman Empire in the First Balkan War, but the putative allies continued to quarrel among themselves. Then in 1913, the alliance split, and the Serbs, Greeks, and Romanians defeated Bulgaria in the Second Balkan War. Austria-Hungary became the patron of Bulgaria, which now was Serbia's territorial rival in the region, and Germany remained the Ottoman Empire's protector. Russia tied itself more closely to Serbia than it had previously. The complex system of alliances and Great Power support was extremely unstable; among the Balkan parties harboring resentments over past defeats, the Serbs maintained particular animosity toward the Austro-Hungarian annexation of Bosnia and Herzegovina.
In June 1914, a Serbian terrorist assassinated Archduke Franz Ferdinand, heir to the throne of Austria-Hungary, which then held the Serbian government responsible. Austria-Hungary delivered an ultimatum to Serbia, believing that the terms were too humiliating to accept. Although Serbia submitted to the ultimatum, Austria-Hungary declared the response unsatisfactory and recalled its ambassador. Russia, fearing another humiliation in the Balkans, supported Serbia. Once the Serbian response was rejected, the system of alliances began to operate automatically, with Germany supporting Austria-Hungary and France backing Russia. When Germany invaded France through Belgium, the conflict escalated into a world war.