The build-up of Russian forces close to the Ukrainian border continues apace, with everything from submarines and amphibious landing ships in the Black Sea to short-range ballistic missiles, tanks and howitzers around Ukraine"s northeastern edges.

CNN has geolocated and authenticated social media videos of these movements - though there are likely many more that are not being observed.

Some of the videos come from official sources. Most are from TikTok or YouTube. They are being analyzed by online observers and often complement satellite imagery. CNN geolocated some videos at the village of Sereteno, about 24 km from the border. They were uploaded on Sunday and show tanks moving through the area.