The TikTok buildup: Videos reveal Russian forces closing in on Ukraine

In areas of Russia and Belarus near the Ukrainian border, onlookers have uploaded hundreds of videos showing sophisticated Russian weaponry and military vehicles speeding by on railways, highways and local roads toward positions near Ukraine.

In recent days, those videos have begun worrying military analysts. The scenes, the military analysts say, appear to indicate that the Russian buildup could be entering its final stages before an invasion. Here is what they are watching.