Current situation at Kerch https://www.marinetraffic.com/en/ais/home/centerx:36.5/centery:45.4/zoom:9
Moscow has been busy building a bridge over the Kerch Strait and a railway upon that bridge. This bridge was deliberately built at a height that all but precludes Ukrainian commercial traffic from operating in the Sea of Azov, thus placing the port of Mariupol in economic jeopardy. And in another contravention of international law, it has declared that it will block any NATO attempt to send ships into the Sea of Azov, even if they are invited by Ukraine.
http://www.atlanticcouncil.org/blogs/ukrainealert/why-is-the-sea-of-azov-so-important
...and in the air https://www.flightradar24.com/45.45,37.22/8