The American empire started as an American continental empire, forcing the Native Americans out via genocide, war, and breaking approximately 500 treaties with a sovereign nation. Then the US empire expanded globally, initiating DOZENS false flag attacks that then led to wars.
The result of empire building is the installation of numerous US friendly vicious, brutal dictators in dozens of countries all around the world.
Another way to take over countries is economically, via economic hit men, and dozens of countries have been taken over by the US empire in this way as well.
Why is it that the US has close to 1,000 foreign military bases, if not for empire building? Only military empires need foreign military bases in the countries that they control.