The diplomatic row between Azerbaijan and Russia illustrates the Kremlin's declining influence in the Caucasus and will increasingly enable competing powers to fill the void, especially if the feud worsens. In recent days, Baku and Moscow have traded tit-for-tat measures that have further weakened their relationship. Problems began on June 27, when Russian authorities arrested dozens of people of Azerbaijani origin, two of whom died after being taken into custody, in connection with a string of unsolved violent incidents in 2001-11. In response, on June 29, Azerbaijani authorities canceled all cultural events with Russian participation as well as two intergovernmental meetings. On June 30, Azerbaijani police raided the office of the Russian state-backed news agency Sputnik over the outlet's continued operation after the rescission of its license earlier this year; police detained seven employees (two of whom were formally arrested) on multiple charges, including espionage, fraud and illegal financing. Eight...