On Monday, pro-Russia protesters stormed a police station in the eastern Ukrainian city of Horlivka. VICE News correspondent Simon Ostrovsky was there as they seized the building. Inside, the demonstrators attacked a police officer accused of pushing someone out of a window while the person was trying to display a Russian flag. Later that day, a video emerged on the internet showing a man purporting to be a Russian army colonel giving orders to troops in eastern Ukraine. This is the first bit of evidence that there might already be Russian boots on the ground in the country.