Azerbaijan shot down two Armenian warplanes on Thursday, the country's Defense Ministry said.
A statement said the Armenian combat aircraft were flying over Azerbaijani positions in the Gubadli direction of the front.
The ministry added that the Su-25 fighter jets were shot down on Thursday afternoon.
Since clashes erupted on Sept. 27, Armenia has repeatedly attacked Azerbaijani civilians and forces, even violating three humanitarian cease-fires since Oct. 10.
The latest humanitarian truce in Upper Karabakh, or Nagorno-Karabakh, an internationally recognized territory of Azerbaijan, came into force last Saturday.
Relations between the two former Soviet republics have been tense since 1991, when the Armenian military occupied Upper Karabakh.
Four UN Security Council resolutions and two from the UN General Assembly, as well as international organizations, demand the withdrawal of Armenian forces from the occupied territory.
In total, about 20% of Azerbaijan's territory-including Nagorno-Karabakh and seven adjacent regions-has been under illegal Armenian occupation for nearly three decades.
The Organization for Security and Co-operation in Europe (OSCE) Minsk Group -- co-chaired by France, Russia, and the US -- was formed in 1992 to find a peaceful solution to the conflict, but to no avail. A cease-fire, however, was agreed to in 1994.
World powers, including Russia, France, and the US, have called for a new and lasting cease-fire. Turkey, meanwhile, has supported Baku's right to self-defense and demanded the withdrawal of Armenia's occupying forces.
