The renewed movements of Russian forces in the area come as the Kremlin embraces a harder line on Ukraine. Russian officials from President Vladimir Putin on down have escalated their rhetoric in recent months, attacking Kyiv’s Western ties and even questioning its sovereignty. Putin has warned that any expansion of NATO military infrastructure on Ukrainian territory represents a “red line” for Moscow…

What the Russian forces gathering near the Ukrainian border are doing is unclear.

Videos have surfaced on social media in recent days showing Russian military trains and convoys moving large quantities of military hardware, including tanks and missiles, in southern and western Russia.

“The point is: It is not a drill. It doesn’t appear to be a training exercise. Something is happening. What is it?” said Michael Kofman, director of the Russia studies program at the Virginia-based nonprofit analysis group CNA.