See Powerful Russian Military In Ukraine

 

I don't support Russia, attacking on land is quite difficult, especially if you're trying to access a different territory. If Russia intensifies air bombardment, Ukraine can only cry for help, but for the sake of civilian casualty, they're stalling on that.

Go ask the American Army what they went through in Mogadishu. The movie Black Hawk Down is based on their experience there... and that was just against a militia, not an army.