US Secretary of State Mike Pompeo on Tuesday called on Armenia and Azerbaijan to fulfill an agreed ceasefire that has not been holding.
"The United States calls on Azerbaijan and Armenia to implement their commitments to a ceasefire as agreed and cease targeting civilian areas, such as Ganja and Stepanakert," Pompeo wrote on Twitter.
"We deplore the loss of human life and remain committed to a peaceful settlement."
Russia has taken a leading role in diplomacy in the heaviest fighting between the former Soviet republics since 1994, with the Armenian and Azerbaijani foreign ministers agreeing Saturday to a ceasefire after 11 hours of talks in Moscow.
But the ceasefire has not held, with Russia, the European Union and Iran earlier all urging both parties to implement it.