Final answer:
Implementing the Marshall Plan without European cooperation could have led to resentment, inefficiency, and strengthened resistance against American influence, counterproductive to its goal of economic rebuilding and containment of Communism.
Step-by-step explanation:
The question explores potential issues if the United States had implemented the Marshall Plan without the cooperation of European countries. Problems that could have arisen include resentment from nations receiving aid, inefficiency due to lack of local support, and unintended geopolitical consequences, such as strengthening resistance to American influence. Without the support and cooperation of European governments, the Marshall Plan might have been seen as an imposition, undermining the intended goals of economic recovery and the containment of Communism.