US Secretary of State Mike Pompeo voiced hope Thursday that Armenia would "defend" itself against Azerbaijan, appearing to show sympathy to one side over the fierce clashes.

"We're hopeful that the Armenians will be able to defend against what the Azerbaijanis are doing," Pompeo said in an interview with WBS radio in Atlanta.

Pompeo voiced hope that the two sides would "get the ceasefire right, and then sit down at the table and try and sort through... what is a truly historic and complicated problem set."

The United States -- which has a strong Armenian diaspora but growing strategic relations with Azerbaijan -- has over the past two weeks voiced neutrality over the violence, urging both sides to talk.

Pompeo renewed criticism of NATO ally Turkey, which has staunchly backed Azerbaijan.

"We now have the Turks, who have stepped in and provided resources to Azerbaijan, increasing the risk, increasing the firepower that's taking place in this historic fight over this place called Nagorno-Karabakh," Pompeo said.

The United States is co-chair of the so-called Minsk Group in charge of diplomacy on Nagorno-Karabakh along with Russia and France.

The foreign ministers of Armenia and Azerbaijan agreed over the weekend to a humanitarian ceasefire, but both sides accused the other of violating the agreement within hours after it was supposed to take effect.

Azerbaijani forces have advanced along the north and south of the front line, taking positions in Karabakh and in two districts of Azerbaijan that have been under Armenian control since 1994.