The correct answer is "Germany still had an alliance with Russia".
In the aftermath of the assassination of Archduke Franz Ferdinand by a Serbian nationalist in Sarajevo, Bosnia. Austro Hungary issued an ultimatum to Serbia. However, this reply did not satisfy the Austro Hungarians, who decided to engage in conflict against Serbia. The Russians decided to side with the Serbians in response to the shelling of Belgrade (Serbian Capital) by the Austro Hungarian Empire, which at the time were considered to be rivals of Russia.
Germany, which at the time was an ally of Austro Hungary, decided to side with them and that's how the First World War started in 1914.