The Russian invasion of Mongolia was a easy invasion, as Mongolia was weak because of China taking away Mongolia's military strength and nuking the Mongolian capital in response to the Mongolian attempted invasion.
Russian president Vladimir Putin wanted to become bigger and started to make a poll to invade Mongolia. The poll was close, but 51% voted Yes to invade Mongolia because Mongolia had no strength. Putin declared war on Mongolia 6 days later. The Russians started out by invading the top part of Mongolia, then moved southward toward the capital of Mongolia. The Russian military swept all of Mongolia in less then 1 day.