America did not have a "stockpile" so to speak, until 1950. And even by then, other non-nuclear powers could afford to toe around the line around it, like China in the Korean war. And I'm not even talking about something as "brash" as that either. The Red Army was practically a stone's throw away from the Greek Civil War and had other means of keeping the West out (ie the fact that communist parties were empowered in newly liberated France and Italy). That alone could have extended WARPAC's reach and possibly averted Yugoslavia's split from the Warsaw Pact, even if there were other sources of tension.

The reason they didn't go through with it was largely because the RKKA reached its near-breaking point and leadership wanted to get reconstruction back on track. Even the slightest provocation is something they were wary of. Which is understandable.