Why, when the US was a First World country with the strongest military wasn't it imperialistic?

Sorry, I wrote up the question pretty poorly last time, please answer it now.

We don't fight to colonize the land and make the countries apart of any major empire.
Update: Last time I asked why the US had skipped the Imperialistic phase, and many people noted that this was not true since the US conquered land from coast to coast and slaughtered millions of people. I ended up deleting that question. I realize it's not true and didn't reflect what I meant to ask. I am sorry... show more Last time I asked why the US had skipped the Imperialistic phase, and many people noted that this was not true since the US conquered land from coast to coast and slaughtered millions of people. I ended up deleting that question. I realize it's not true and didn't reflect what I meant to ask. I am sorry about that.

Above is the question I meant to ask.
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