In the late 1940s to the mid-1950s, the major US foreign policy was the policy of containment of communism. This policy of containment was accomplished through a variety of practices including foreign economic aid, military aid, and at times, covert action against governments such as those of Iran and Guatemala.
These influenced foreign relations because they helped turn many incidents that would otherwise have been of no global consequence into important events.
For example, the civil war in Greece would normally have been of no consequence to the world as a whole. However, when seen through the lens of containment, it became an issue that could attract support for its various sides from both the US and the USSR.
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