The United States Department of State has described Azerbaijan's advancement into Armenia's territory as "irresponsible" and "unnecessarily provocative".

Principal Deputy Spokesperson Jalina Porter said the State Department is closely monitoring the situation along the demarked border between Armenia and Azerbaijan.

"Military movements in disputed territories are irresponsible, and they’re also unnecessarily provocative," Porter said.

"Of course we’ve seen the reports of some withdrawal and would welcome that, if confirmed, but we expect Azerbaijan to pull back all forces immediately and cease further provocation."

Porter said the U.S. has also urged "both sides" to approach demarcation issues through discussion as well as negotiation.

On the morning of May 12, the armed forces of Azerbaijan violated the border of Armenia in the southern province of Syunik, advancing 3.5 kilometers and surrounding Sev Lake, which is situated on the border between the two countries but is predominantly a part of Armenia. On May 13, the Azerbaijani military committed more border violations against Armenia, advancing near Vardenis (Gegharkunik province) and Sisian (Syunik province).