The оperation "Ring" for the deportation of the indigenous population

In April-August 1991, special police detachments of the Azerbaijani Interior Ministry, together with units of the internal troops of the USSR Interior Ministry and the 4th Army initiated a large-scale military-police operation "Ring" to forcibly evict the residents from the Armenian settlements of Artsakh.

The decisions to deport residents of a number of Armenian-populated villages in the NKAO and adjoining districts were taken by the leadership of the Azerbaijani SSR in April 1991. The leadership of the deportation operations was assigned to Azerbaijani Minister of Internal Affairs M. Asadov.

It should be added that the Azerbaijani leadership considered the "Ring" operation as the beginning of a large-scale deportation of the remaining Armenian population of Nagorno Karabakh. And on April 30 for the first time tanks, combat helicopters and artillery were used against the peaceful population of Artsakh, and the first targets were the villages of Getashen and Martunashen.
Soviet Military in Artsakh in 1991

The Armenian villages were surrounded one by one by the internal troops of the USSR Interior Ministry and the Soviet Army. Then, ostensibly for the purpose of "checking the passport regime", the Azerbaijani OMON and police entered those villages. In reality, the goal was not to check anything, but the subsequent deportation of the population.

As a result of the operation more than two dozen Armenian villages of the historical Northern Artsakh, as well as Shahumyan, Hadrut and Shushi districts were completely deserted and destroyed, almost ten thousand people were displaced, more than 100 were killed, several hundred people were taken as hostages. The fate of many of them is still unknown.
Conclusions: In response to the use of violence and deportation of the population, the indigenous Armenian population decided to defend themselves. Thus the war began.