<span>The modern Republican party was born from these individuals. The modern Republican party was formed in 1854 by anti-slavery enthusiasts and the like. The Republican party formed in the wake of the Whig party that eventually faded out after its demise in the 1800s. The Republican party was a Northern party, while the Democratic party was largely in the South.</span>
Answer:
Constitution is the answer
The correct answer to this open question is the following.
Although you did not specify the time in history or any specific context, we are going to assume that you are referring to the US imperialistic role through history.
Being that the case, we can comment on the following.
The foreign policy actions of the United States reflect selfish, imperialist ambitions since the times of President James Polk and the Manifested Destiny. He expanded the US territory acquiring the Mexican northern states after the Mexican-American War.
Since those years, passing through the times of President Monroe and the Monroe Doctrine and President Theodore Roosevelt and his Roosevelt corollary, the United States has always had interventionist purposes as part of its foreign agenda.
Nobody has granted the US the right or role to be the "big brother" who was looking after the interests of the western hemisphere. That is why the US has had many problems throughout history in the Middle East, Latin America, Europe, and other regions.
