"The U.S. condemns the confrontation on the Azerbaijani-Armenian border and calls on the parties to immediately stop the use of force," said Press Secretary of the U.S. Department of State Morgan Ortagus said in a statement. 

The statement reads: "The U.S. harshly condemns the aggression on the Azerbaijani-Armenian border. We call on the sides to immediately stop the use of force, use the existing direct communication channels between each other and strictly abide by ceasefire.  As the OSCE Minsk Group Co-chair, the U.S. is committed to helping the consistent and peaceful resolution of the Nagorno-Karabakh conflict. To achive this goal, we will continue to actively participate in these efforts. The U.S. joins the calls of the Minsk Group Co-chairs to resume negotiations in a short period of time and highlights the importance of the return of the OSCE observers to the region."