In the beginning of 1920, Sultanov intensified his efforts to bring control of the region under Azerbaijani rule by issuing an ultimatum to the Armenian National Council. In early 1920, the Paris Peace Conference had recognized Azerbaijan's "de facto" claim to Karabakh. But since the conference had ended without issuing a conclusive decision on Karabakh, Sultanov advocated for a local solution, one which demanded that the region be incorporated into Azerbaijan. He bolstered the size of the garrisons at Khankendi and continued to move his troops around, once more without the required consent of his administrative council. Ethnic tension in Karabakh heightened once more, as Azerbaijani troops lynched and killed several Armenians in Khankendi and pillaged the surrounding areas in February of that year. In early March, after a delegation of Karabakh Armenians met in the village of Shosh and rejected the possibility of union with Azerbaijan, Sultanov sought to tighten his control of Karabakh: he forbade Armenians from leaving Shusha without permission, stationed Azerbaijani troops in Armenian homes, ordered Armenian veterans of the former Russian Army to register so that they may not partake in military activities, and drew up plans to destroy several Armenian villages to sever the link between Armenians in Karabakh and the region of Zangezur. In March 1920, mass killings of the Armenian population took place in the Shusha massacre.