Passage: Speaking at the Paris Peace Conference on October 10, 1946 Molotov had already stated Soviet fears: "If American capital was given a free hand in the small states ruined  and enfeebled by the war [it] would buy up the local industries, appropriate the more attractive Rumanian, Yugoslav ... enterprises and would become the master in these small states." While the Soviet ambassador in Washington suspected that the Marshall Plan could lead to the creation of an anti-Soviet bloc, Stalin was open to the offer. He directed that—in negotiations to be held in Paris regarding the aid—countries in the Eastern Bloc should not reject economic conditions being placed upon them. Stalin only changed his outlook when he learned that (a) credit would only be extended under conditions of economic cooperation and, (b) aid would also be extended to Germany in total, an eventuality which Stalin thought would hamper the Soviets' ability to exercise influence in western Germany.Initially, Stalin  maneuvered to kill the Plan, or at least hamper it by means of destructive participation in the Paris talks regarding conditions. He quickly realized, however, that this would be impossible after Molotov reported—following his arrival in Paris in July 1947—that conditions for the credit were non-negotiable. Looming as just as large a concern was the Czechoslovak eagerness to accept the aid, as well as indications of a similar Polish attitude.Stalin suspected a possibility that these Eastern Bloc countries might defy Soviet directives not to accept the aid, potentially causing a loss of control of the Eastern Bloc. In addition, the most important condition was that every country choosing to take advantage of the plan would need to have its economic situation independently assessed—a level of scrutiny to which the Soviets could not agree. Bevin and Bidault also insisted that any aid be accompanied by the creation of a unified European economy, something incompatible with the strict Soviet command economy.

Question: which nation made it hard to unify a European economy?
Soviet