Armenia and the breakaway republic of Nagorno-Karabakh previously declared martial law and general mobilisation, while Azerbaijan declared partial martial law and partial mobilisation, closing its airports to all countries except Turkey.

Both sides report continuing clashes in Nagorno-Karabakh, with numerous photos and videos of the fighting from Monday and Sunday published on social media. Azerbaijan has claimed that Armenian forces lost 550 servicemen, while Armenia reported only several dozen casualties, adding that Baku had lost hundreds of soldiers.

The UN Security Council plans to convene later in the day in order to address the clashes, according to media reports.

Nagorno-Karabakh, an Armenian-majority autonomy, proclaimed independence from what was then Soviet Azerbaijan in 1991. A major conflict between Baku and Yerevan ravaged the area until 1994 when the sides agreed to start peace talks mediated by the OSCE Minsk Group. However, the ties between the two nations have remained tense due to the frozen conflict.