Answer:
Fighting a tyrannical foreign power
Step-by-step explanation:
Assuming you mean JFK (best president of all time, absolute chad) he was likely talking about how the American people need to unite to fight the Tyranny of the USSR (very cringe and smelly, lots of dead serfs.) Also was probably talking about how it's important to value American ideals such as freedom and liberty. Likely because Communism was growing fast (also bad, no freedom and also basically the opposite of the American economy)