evidence: On Sept. 19, Azerbaijan launched a large-scale military offensive against the autonomous ethnic Armenian enclave of Nagorno-Karabakh, known in Armenia as Artsakh. Within 24 hours, Azerbaijan secured effective control over Nagorno-Karabakh, and the Artsakh Defense Army was disbanded. These seismic events ended a three-decade frozen conflict, which included large-scale wars from 1988-1994 and in 2020, and resulted in the exodus of almost all ethnic Armenians in Nagorno-Karabakh to Armenia. [...] While the strategic picture is relatively optimistic for Turkey and potentially problematic for Iran, the implications of Azerbaijan’s takeover of Nagorno-Karabakh for Russia are less clear. Russia’s security guarantees, which date back to a 1997 treaty with Armenia, only apply to Armenia’s internationally recognized territory. Even though Russia’s passive response to Azerbaijan’s May 2021 incursions into Syunik undermined these security guarantees, the security pact categorically does not extend to Nagorno-Karabakh, which is legally part of Azerbaijan. But Pashinyan, the Armenian prime minister, still denounced Moscow’s inaction. Pashinyan publicly criticized Russia’s unreliability as an ally and highlighted the degradation of Russia’s military capabilities in Ukraine. The relationship has continued to decline: After the deaths of five Russian peacekeepers in an accidental clash with the Azerbaijani Armed Forces, Russia dismantled its observation posts in Nagorno-Karabakh on Oct. 5.