In Shusha, Erdogan and Aliyev held talks and signed a declaration “on allied relations” between the two countries aimed at deepening ties in several areas of cooperation, including security.

“Today is a historic day,” Aliyev said after the signing. “The declaration raises our relations to the highest level.”

Turkey actively supported Azerbaijan in the last war over Nagorno-Karabakh. After six weeks of fighting that killed more than 6,000 people, Azerbaijan regained control of much of the region and Armenian-held surrounding territories.

Erdogan, the first foreign leader to visit Shusha after it was retaken by Azerbaijan, also promised to open a Turkish consulate in the city. “In that way, we will ensure that our activities are carried out faster and more effectively,” he said.

Nagorno-Karabakh lies within Azerbaijan but was under the control of ethnic Armenian forces backed by Armenia after a separatist war there ended in 1994.

A Russia-brokered peace deal that ended the hostilities last November was celebrated as a triumph in Azerbaijan. But it sparked a political crisis in Armenia, with thousands of opposition supporters taking to the streets to protest the terms of the deal and to demand the resignation of Armenia’s Prime Minister Nikol Pashinyan.

Under pressure to step down, Pashinyan called snap elections, and the vote is scheduled to take place on June 20.

Armenia’s Foreign Ministry on Tuesday condemned Erdogan’s and Aliyev’s visit to Shusha in a statement, calling it “provocative actions” that “significantly harm international efforts to establish stability in the region and (that) are absolutely unacceptable.”