Between 1938 and 1940, following German–Italian mediation in the First and Second Vienna Awards, and the Hungarian invasion of Carpatho-Ukraine, Hungary enlarged its territory. It absorbed parts of southern Czechoslovakia, Carpathian Ruthenia and the northern part of Transylvania, which the Kingdom of Romania ceded. One of the ethno-cultural areas that changed hands between Romania and Hungary at this time was the Székely Land. The support that Hungary received from Germany for these border revisions meant that the relationship between the two countries became even closer. On 20 November 1940, Hungary formally joined the Axis Tripartite Pact. On 12 December 1940, at the initiative of the Prime Minister, Count Pál Teleki, Hungary concluded a friendship and non-aggression treaty with Yugoslavia. Although the concept had received support from both Germany and Italy, the actual signing of the treaty did not, as Germany's planned invasion of Greece would be simplified if Yugoslavia could be neutralised. After the Yugoslav military coup of 27 March 1941, when the Germans asked the Hungarian Regent, Miklós Horthy, for clearance to launch one of their armoured thrusts using Hungarian territory, Teleki was unable to dissuade the Regent. Concluding that Hungary had disgraced itself irrevocably by siding with the Germans against the Yugoslavs, Teleki shot and killed himself. Horthy informed Hitler that evening that Hungary would abide by the friendship treaty with Yugoslavia, though it would likely cease to apply should Croatia secede and Yugoslavia cease to exist.