In March 1923 Stamboliyski signed an agreement with Yugoslavia recognising the new border and agreeing to suppress VMRO. This triggered a nationalist reaction, and on 9 June there was a coup after which Stamboliykski was assassinated (beheaded). A right wing government under Aleksandar Tsankov took power, backed by the Tsar, the army and the VMRO, who waged a White terror against the Agrarians and the Communists. The Communist leader Georgi Dimitrov fled to the Soviet Union. There was savage repression in 1925 following the second of two failed attempts on the Tsar's life in the bomb attack on Sofia Cathedral (the first attempt took place in the mountain pass of Arabakonak). But in 1926 the Tsar persuaded Tsankov to resign and a more moderate government under Andrey Lyapchev took office. An amnesty was proclaimed, although the Communists remained banned. The Agrarians reorganised and won elections in 1931 under the leadership of Nikola Mushanov.