At the end of WW2, Hungary and Czechoslovakia were both liberated from German occupation (having been occupied since 1938 for the majority of Czechoslovakia and since 1943 for Hungary, who before that were axis members) with relatively little help from internal resistance movements in the countries. There was resistance in both countries, but it wasn’t significant, and the soviets were the predominant force setting up the post occupation government structures.

The Hungarian election is 1945 were pretty bad for soviet aligned parties, taking only around 17% of votes. However the structures that the ussr had been able to set up in the country while occupied by the Red Army allowed them to form a puppet government aligned with the USSR.

In Czechoslovakia the communist party had quite decent support, and came out as the leading party in the 1946 elections, with 38% of the vote, the highest ever vote share received in the Czech parliament. However by 1948, with the country beginning to flirt with more western ideals, the soviets backed a communist coup d’état, which established the communists as the sole political party.

In Yugoslavia things were quite different. The Yugoslav partisans, headed by Josip Tito, had been ferociously fighting the axis occupiers since practically the beginning of the occupation. In 1942 the partisans formed the Anti-Fascist Council for the People’s Liberation of Yugoslavia (AVNOJ) and claimed the status of the country’s parliament.

The partisan resistance movement survived significant efforts of axis forces in 1943, including full scale engagements involving up to 150,000 axis soldiers. Their success grew their popularity, and their own forces continued to grow. Upon Italy surrendering in late 1943, the Yugoslav forces liberated the territories of their country that had been under Italian occupation, capturing a lot of Italian weaponry and gaining further volunteers.

In late 1943 the AVNOJ met again and proclaimed the aim to establish the Democratic Federal Yugoslavia, with recognition and promises of supplies secured during the Tehran conference, and elections set for late 1945.

While the Red Army provided crucial help in liberating the capital Belgrade, much of the rest of the country was liberated directly by the Yugoslav partisans, and by the end of the war the country was fully controlled by Tito’s forces, with some small areas of Italy and Austria occupied by the Yugoslavs. The soviets had minimal control over state apparatuses in the same way they had secured in Hungary and Czechoslovakia.

The Yugoslavian elections in 1945 had plenty of shenanigans involved, however these were entirely orchestrated internally, rather than with support from the USSR. The outcome was the establishment of a one party state in Yugoslavia, with Tito in control, who was a close ally to the USSR initially.

What all this meant was that Tito’s power base was independent of the USSR, unlike that of Hungary and Czechoslovakia. While they shared an ideology, Yugoslavia was not a puppet state in the same way.

So when the Tito - Stalin split began to become apparent in 1948, it was not so much Yugoslavia rejecting a USSR imposed government, more so Yugoslavia trying to carve out its own spheres of influence in the Balkans, particularly Albania and Greece.

Of course, none of this fully explains why Stalin wasn’t willing to use force against Tito and Yugoslavia to bring them into line with the rest of the soviet bloc. The clearest connection is that the USSR did not have the same influence upon the Yugoslav communist party as they had in Hungary and Czechoslovakia. While there were significant numbers of Stalinists among the Yugoslav communists, once the dispute between Stalin and Tito heated up Tito was quick to act and aggressively began purging Stalinist sympathisers from the party, known as the “informbiro period”. But throughout, most communists in Yugoslavia were Tito supporters thanks largely to his wartime exploits.

Another major reason no intervention took place was that the USSR was still recovering themselves from the war. It had been less than five years since the end of WW2 when the split became apparent, and Stalin felt he could not commit the necessary forces or resources for such an operation on top of other commitments. The most obvious of these was the Korean War, which was taking place simultaneously to this dispute. Yugoslavia itself was similar in geography to Korea, with defensible, mountainous terrain, and the Yugoslav army was battle experienced and had proven its abilities both in conventional and guerrilla warfare.

What’s more, it was entirely possible Yugoslavia would have western military support, as the western powers, in particular Britain, wanted to deny Russia access to a warm water port in the Mediterranean. Yugoslavia’s position next to NATO member Italy, and with a long coastline would allow the west to supply or maybe even send soldiers to the country easily. This seemed increasingly likely as Yugoslavia was included into the US backed Mutual Defence Assistance Program in 1951.

On top of these factors, it was less important for the USSR to intervene on a strategic level than if, for example, Yugoslavia was flipping to the west. Tito was still ruling as a socialist, and was therefore not implicitly as threatening to the bloc. An attempt at military intervention could easily change this, pushing the country into siding with the west rather than becoming (as it did) a founding and leading member of the “non-aligned” movement of countries.

All this said, the soviets did in fact back at least one attempted coup of Tito at the beginning of the splits in 1948, with the support of the Yugoslav chief of the general staff, Arso Jovanović. This attempt however was foiled and Jovanovic was killed while attempting to flee to Romania.

So in short, the USSR did try to coup Yugoslavia in a similar way to Hungary and Czechoslovakia, but their limited influence in the Yugoslav communist party coupled with Tito’s popularity meant they were unsuccessful, and therefore couldn’t bring the country back into their alliance without a full scale military engagement. They were not willing to risk this due to the possibility of western intervention, commitments elsewhere on the geopolitical stage, and still needing time to recover from WW2.