There can be some negative effects of following a policy of imperialism. When an imperialist power conquers or controls a country, there may be problems if that country doesn’t want to be controlled. For example, when the United States got control of the Philippines after the Spanish-American War, the people of the Philippines rebelled. They wanted to become free. We had to subdue the rebellion. There were costs associated with subduing the rebellion.
Imperialism may also become expensive over a period of time. The longer the imperial power stays, the more costs associated with the occupation. This happened to the British when they had the American colonies. In the beginning, the British made a lot of money from the colonies. Eventually, the cost of running the colonies increased, and the British wanted the colonists to pay some of those costs. Passing laws requiring the colonists to pay some of the costs of running the colonies eventually led to the beginning of the Revolutionary War.
Finally, being an imperial power may lead to a negative public opinion of the imperial power and subject it to attacks. This is especially true if the people don’t want the imperial power in the country. The United States and Britain are often viewed negatively because of their imperialistic actions and influence throughout the world. This has subjected these countries to an increased threat of terrorist attacks.