That's nothing lets see them enter beyond where the rebels hold the land where Ukrainian arty are well positioned and backed by 40-50k troops.
Putin recognizes all of Donetsk and Luhansk as independent not just the small parts held by the "rebel scum."
Think about it... Russia hasn't really faced a "proper military" post WW2 they have taken on guerilla's and guerilla style militaries but not a nation with an actual military no matter how small Ukraine's military really is.
If Russia is the military they claim to be then when they invade the Eastern part of Ukraine it should go as smoothly as the US military during 1991's Desert Storm when US flew halfway around the world to take on the 4th largest army which was battle harden. Also Baghdad had the second most dense IADS at that time second to Moscow. US and so called experts expected thousands of US deaths in that war but only 143 were actually killed in action so it shouldn't be too hard for Russia and likely wont suffer a lot of casualties, eh?