Question

Which Soviet action during the early years of the Cold War almost led to a direct war between it and the United States?

Answer 1

Probably the Berlin Blockade when the Soviets closed off the ground routes to West Berlin (the entire city was inside their occupation zone at the end of the war). It was highly provocative and a number of military options were even considered (and thankfully put aside) before it was decided to settle on the airlift to supply the city with goods. No one wanted it to escalate into WW3, so the airlift was seen as the safest option.