1. The Soviets were not trying to plant a communist
government in Greece in 1946. According to historian Lawrence S. Wittner, the Soviets opposed the idea of supporting the communists in postwar Greece.
This was despite the fact that these Greek communists had led the antifascist
WWII resistance when Greece was occupied by the Nazis. After the
war the Soviets were trying to convince other communist governments
like Yugoslavia not to support the Greek communists.
2. The existing government in Greece in 1946 was a British puppet government, not a sovereign Greek government.
3. The US was trying to and did plant a US puppet government in Greece in 1946.
The US actually wrote the request for help from the Greek puppet government
to the US which the Greek puppet government then publicly delivered to the US.
Wittner, Lawrence S. American intervention in Greece, 1943-1949 (New York: Columbia University Press. 1982).