Your argument isn't logically sound
In fact, it isn't even valid. Given the premises:
The President is the boss regarding US foreign policy.
President Truman supported the establishment of Israel.
The Truman administration officially supported establishing Israel in words and deeds.
______________________________________________________________
You conclude: "It wasn't American foreign policy to support the establishment of a Jewish state, . . ."
How do you logically arrive at that conclusion from the premises? Your statement -- "what I said was correct" -- seems to be a denial of reality.