Armored personnel carriers bristling with weapons line a highway in southern Russia. Rows of tanks are parked beside major roads. Heavy artillery is transported by train.
Videos of military movements have flooded Russian social media for the past month, shared by users and documented by researchers.
And Western governments are trying to find out why. The movements appear to be the largest deployment of Russian land forces toward the border with Ukraine in seven years, according to the U.S. government.