April 07, 2021 11:11 GMT Russian airborne troops take part in exercises in Crimea on March 19. Train convoys of heavy Russian military equipment, seen on multiple videos on social media, reportedly shipping from Siberia to the border regions of Ukraine. The Kerch Strait Bridge to the occupied Crimean Peninsula shut down briefly, apparently for a major shipment of weaponry. An uptick in shelling along the line of control separating Ukrainian forces from Russia-backed fighters in eastern Ukraine. Ominous rhetoric on Russian state TV. Is the Ukrainian-Russian “cold war” about to go “hot”? Amid talk of war, here are six questions framing the flareup in tension between Russia and Ukraine — and some potential answers.