Tension that erupted Nov. 25 between Russia and Ukraine in the Black Sea’s Kerch Strait is continuing, as other countries assess how the row might affect their own situations. The increasing pressure there reminds people of the Russia-Georgia clashes of August 2008.

The critical Kerch Strait allows access from the Black Sea to the Sea of Azov, an internal sea of Russia and Ukraine. The strait brought the two countries face to face that day, when a Russian ship rammed a Ukrainian tugboat, seizing it and two of Ukraine's small armored artillery vessels, as well as two dozen crew members, six of whom were injured. Russia is still holding the vessels and crew.

The 33-kilometer (20-mile) strait also allows access to Azerbaijan, Turkmenistan and other Central Asian and Caucasus countries via Russia’s Don and Volga rivers. In short, the Kerch Strait is a vital vein for the economies of at least 10 countries.

Use of the Azov Sea and Kerch Strait is governed by an agreement between Russia and Ukraine ratified in 2003. The then-friendly Russian Federation and Ukraine signed a treaty of cooperation granting freedom of navigation to merchant ships, warships and state noncommercial vessels flying the flag of the Russian Federation or Ukraine.