On March 23, 1923 he signed the Treaty of Niš with the Kingdom of Serbs, Croats and Slovenes and undertook the obligation to suppress the operations of the IMRO carried out from Bulgarian territory. On 9 June 1923, Stamboliyski's government was overthrown by a coup composed of the right wing factions of the Military League, IMRO, the National Alliance, and the army led by Aleksandar Tsankov. Italian agents sent by Mussolini in retaliation against Stamboliyski's refusal to ally with him against Yugoslavia also aided in the coup. With the Communist faction refusing to intervene and the international community uninterested, Stamboliyski was isolated.