The united states and the soviet union became the two superpowers following world war ii. what did they do to go about defending their position to one another and the world?

What they did in order to defend their position includes a number of things.

I'd start with keeping a sphere of influence: each wanted to have a sphere of economic, political and cultural influence: the two spheres were separated in Europe by the Iron curtain, one of most heavily protected borders on earth. The US supported their sphere with economical growth, and the SU made sure that their sphere is kept more by coercion, e.g. not allowing emmigration.

Second, they led proxy wars (wars in other parts of the world, such as Korea and Vietnam), in which the two powers tried their powers against each other, without direct conflict, which would be too risky for the two powers.

Finally, both developed nuclear weapons and had a sort of "competition" on the number of weapons, which was a symbol ( and an investment) into their strength.

A) the gas is compressed