Fighting between Armenia and Azerbaijan broke out Sunday around the separatist region of Nagorno-Karabakh and the Armenian Defense Ministry said two Azerbaijani helicopters were shot down.

Ministry spokeswoman Shushan Stepanyan also said Armenian forces hit three Azerbaijani tanks.

Nagorno-Karabakh is an ethnically Armenian enclave within Azerbaijan that has been out of Azerbaijan’s control since the end of a war in 1994.

Both sides have heavy military presence along a demilitarized zone separating the region from the rest of Azerbaijan.

Stepanyan said the fighting Sunday began with an Azerbaijani attack, but Azerbaijan said the Armenian side attacked and that Azerbaijan launched a counteroffensive.

The news was harshly received in Turkey.

Turkey’s ruling party spokesman Omer Celik tweeted: “We vehemently condemn Armenia’s attack on Azerbaijan. Armenia has once against committed a provocation, ignoring law.” He promised Turkey would stand by Azerbaijan and said, “Armenia is playing with fire and endangering regional peace.” Turkish presidential spokesman Ibrahim Kalin also took to Twitter, condemning Armenia.

“Armenia has violated the ceasefire by attacking civilian settlements … the international community must immediately say stop to this dangerous provocation.”