Annex: to add or attach something, such as territory, to a larger entity, such as a country or state.
Diplomacy: the art or practice of conducting negotiations between countries or groups in order to reach agreements or resolve conflicts.
Manifest Destiny: a 19th-century belief that it was the destiny of the United States to expand its territory and spread its values and institutions across the North American continent. This belief was often used to justify the acquisition of new territories through annexation or war.