(Not related just helpful. can't not is a double negative. "I can't not leave'' means I can leave)
The biggest reason is probably we can even travel to Mars. Mars is only one planet away from us. the distance is to far for fuel and time. we would need to go much faster and a lot less fuel just to get to Mars.
Truman presents American policy as both offensive and defensive. Because he makes it known to the Soviets that America is standing up against Communism, Thus by showing the Soviets what America is really made of. He uses the word contain to address how communism is. He doesn't want communism to die or grow rapidly, But he wants it to stay at the level it currently is at shortly after WWII.
Hope this helps! :)
