Stalin felt threatened by Tito’s effectiveness and support for Greek communists. He wanted to depose Tito. There were proxy wars, border incursions, assassination attempts, and 80,000-soldier military drills. There were enormous purges of spies or suspected spies with many people getting executed. In the Eastern block, the “Titoists” became the enemy of the day for a while.
NATO decided to defend Tito, even though he was communist because Yugoslavia was a buffer to Italy and Greece. Starting in 1950, NATO provided military aid and drafted a plan to make their line of defense of Europe within the territory of Yugoslavia.