One unit of “military defense equipment” of the ethnic Armenian Karabakh defense army was partially damaged during a guided missile strike launched by Azerbaijani armed forces on Monday, according to Defense Ministry officials in Yerevan and Stepanakert.

In a Facebook post Artsrun Hovannisian, a spokesman for the Armenian Defense Ministry, said the incident happened in the afternoon as Azerbaijani armed forces opened fire at one of the Armenian defense facilities located in the eastern direction of the heavily militarized line of contact.

The official initially did not specify what kind of military hardware was hit by the Azerbaijani fire. Later, he told RFE/RL’s Armenian service (Azatutyun.am) that Azerbaijan launched three Spike missiles and only one of them hit the target. He said it inflicted only insignificant damage on an Osa air defense system, while destroying a vehicle that did not have to do with the system.

Earlier, Azerbaijan’s Trend news agency quoted the country’s Defense Ministry as saying that an Armenian Osa air defense system, a supply vehicle and its crew were destroyed. The Ministry added that the system’s deployment near the line of contact was a “provocation” and a threat to Azerbaijani aircraft.

Both Hovannisian and his Karabakh counterpart Senor Hasratian denied that there had been casualties on the Armenian side as a result of the Azerbaijani strike.

In an identical message posted on their Facebook accounts both officials said: “We state that the provocation of the Azerbaijani armed forces will not remain unanswered, while the entire responsibility for the consequences will lie with the military-political leadership of Azerbaijan.”

The report about the latest incident in Karabakh comes amid heightened tensions in the Armenian-controlled region that broke free from Baku’s control in the early 1990s, triggering a three-year war that killed an estimated 30,000 people on both sides.

The Armenia-backed Karabakh military and Azerbaijani armed forces clashed in April 2016 in what was later dubbed as a four-day war that killed dozens on both sides.

An internationally mediated negotiation process on the issue spearheaded by the United States, Russia and France as co-chairs of the Organization for Security and Cooperation in Europe’s Minsk Group has yielded no tangible result in resolving the conflict yet.