Answer:
Truman Doctrine
Step-by-step explanation:
The Warsaw Pact was an alliance between Nazi Germany and Soviet Russia that agreed to non-aggression and a joint invasion of Poland. It was ultimately void by the time Germany launched its surprise campaign against the Soviets.
The Fourteen Points was a statement of principles for peace that was to be used for peace negotiations in order to end World War I.
The Truman Doctrine, implemented after WWII, outlined the US's commitment to prevent the spread of Communism and was often considered the unofficial declaration of war that began the Cold War. Such plans were implemented because of fear from the "domino theory."
The League of Nations was the precursor to the UN, ultimately being established by the US after WWI to prevent another conflict like WWI from happening again.
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Thus the Truman Doctrine is the best answer.
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