There has been a burst of diplomatic activity in recent months over the territory of Nagorno-Karabakh, which Armenia and Azerbaijan have disputed for decades. Russia, the strongest power in the Caucasus, has become more engaged in the issue as Azerbaijan's leverage in the region grows. Russia's involvement could herald a change in this longstanding conflict. In 1994, after mediation by numerous external players including Russia, Turkey and Iran, a cease-fire was reached to end the conflict. But by that time Armenian forces had decisively defeated Azerbaijan, leading to the de facto independence of Nagorno-Karabakh and Armenian control of several provinces bordering the region. Now, as Russia and the West confront each other over Ukraine, the Nagorno-Karabakh dispute represents a subtler yet similarly significant issue for the Caucasus.