The balance in the Caucasus is changing. With Iran emerging from the malaise of sanctions, it is reaching north and becoming more assertive. Russia, too, is changing tack, aligning with Azerbaijan instead of Armenia in the long-running Nagorno-Karabakh conflict. In early August, Azerbaijan made a bid to capitalize on these changes by hosting the presidents of Iran and Russia for a summit in Baku. The meeting featured discussions of counterterrorism initiatives and of the negotiations on Nagorno-Karabakh and Caspian Sea disputes. But it was regional connectivity -- not conflict -- that topped the agenda, specifically the North-South Transport Corridor and its railway construction component....