Why did Otto von Bismarck negotiate the Reinsurance Treaty with Russia in 1887?

Otto von Bismarck negotiated the Reinsurance Treaty with Russia in 1887 primarily to prevent a strategic nightmare for the German Empire: a two-front war caused by a potential alliance between France and Russia.1

Following the collapse of the Dreikaiserbund (Three Emperors’ League) due to escalating tensions between Austria-Hungary and Russia over their competing interests in the Balkans, Bismarck sought to maintain influence in St. Petersburg. By securing this secret agreement, he aimed to ensure that Germany would not be drawn into a conflict between its two eastern neighbors while simultaneously keeping Russia diplomatically isolated from France.213

The treaty stipulated that both Germany and Russia would remain neutral if the other became involved in a war with a third great power, with the critical exception that this neutrality would not apply if Germany attacked France or if Russia attacked Austria-Hungary. Through this "virtuosity" of diplomacy, Bismarck attempted to stabilize Europe by balancing the conflicting ambitions of the major powers.213