Why did the Russian provisional government keep Russian troops involved in world war 1 after Russian revolution of 1917

After the assassination of Archduke Franz Ferdinand, the Austro-Hungarian Empire declared war on Serbia, but it had an alliance with Russia, which in turn declared war on the Austro-Hungarian Empire. Since the nineteenth century there was a strong policy of alliances between the major European nations, the following are followed by declarations of war between them until the conflict reaches that proportion we know: world.

Although Russia entered the war, its internal situation was not the most favorable, but the Russian provisional government decided to keep in battle because of the alliance with Serbia and the declaration of war of the Austro-Hungarian empire.