Answer:
This was because they blatantly rejected the plan
Step-by-step explanation:
The Marshall Plan was set up in 1947 by the then Secretary of State George C. Marshall. The plan involved the United States providing assistance to European countries which were hugely hit by the war.
The Eastern bloc countries which includes the Soviet Union didn’t support plan because they had worries of representation of a form of imperialism and economic dominance by the Americans. Other countries such in the Eastern bloc region such as Poland and Czechoslovakia also refused the plan.