Why was US concerned about one nation controlling so much oil?

The U.S. was concerned about one nation controlling a significant portion of the world's oil due to the potential for that nation to wield disproportionate economic and political power, which could disrupt global markets and energy supplies. This monopoly could lead to higher oil prices, threaten U.S. energy security, and undermine the stability of allied nations dependent on oil imports. Additionally, such control could enable the nation to exert influence over geopolitical dynamics, potentially challenging U.S. interests and global stability.