BAKU, Oct. 17 -- Kazakhstan gained an additional route for its data to Europe on Thursday, and the governments that built it have not said what it finally cost or how much traffic it will carry. Presidents Kassym-Jomart Tokayev and Ilham Aliyev launched a 380-kilometer fiber-optic line across the floor of the Caspian Sea, Kazakhstan's presidential office said.

The launch came on the day of the Baku CICA summit, and a second document changed hands beside it. In the presidents' presence, the two governments exchanged a signed agreement on developing the Trans-Caspian International Transport Route, the freight corridor better known as the Middle Corridor.

Tokayev framed the cable as something other than freight. It is "not a transport corr...