As purges continue across Turkey in the wake of the attempted military coup, the leaders of certain countries are attempting to defend and solidify their holds on power. But one need look no further than Turkey's immediate periphery in the Caucasus and Central Asia to see evidence of their efforts. On Wednesday, Azerbaijani President Ilham Aliyev unveiled constitutional amendments to prolong presidential terms from five to seven years, while Turkmen President Gurbanguly Berdimukhammedov set a date for a similar presidential term extension to take effect in his country. It is no coincidence that the leaders of Azerbaijan and Turkmenistan are pursuing a greater centralization of power, much as Turkish President Recep Tayyip Erdogan has in recent years. In part, a perceived increase in external security threats is driving the centralization efforts in these countries....