Bulgaria's expansion into Macedonia in 1941-44 started a new phase of the Macedonian Question, which did not end with the defeat of the Axis. From 1942 on, new developments took place within the Yugoslav and Bulgarian resistance movements, controlled by the Communists.
The old rivalry between Sofia and Belgrade over supremacy in the Balkans and control of the region of Macedonia emerged again with the competition between the two Communist parties during the Occupation and immediately after.
The fact that Bulgaria had sided with Hitler worked in favour of the Yugoslavs, who tried to control the resistance movement in all three parts of Macedonia (Greek, Yugoslav and Bulgarian). Just as it had happened in the inter-war period, the problems confronting Greek-Macedonia arose as a result of the rivalry between Yugoslavia and Bulgaria and of their aspirations to control the northern Aegean coastline.