Imperialism: Imperialism is a policy or ideology advocating for extending a nation's power through territorial acquisition or by gaining control over other countries' political or economic systems.
Monroe Doctrine: The Monroe Doctrine was an American foreign policy statement issued in 1823 that warned European nations against interfering with independent countries in the Americas.
Open Door Policy: The Open Door Policy was a U.S. foreign policy in the late 19th and early 20th centuries that advocated for equal trading rights and access to China's market among various imperial powers.