Which concept states that a country has the moral obligation to expand its territorial boundaries at all costs?

The concept you are referring to is called "Manifest Destiny." To understand the concept of Manifest Destiny, it is important to delve into its historical context and the events surrounding it.

Manifest Destiny was an ideology that emerged in the 19th century in the United States. It is the belief that the United States was destined, or even divinely ordained, to expand its territorial boundaries from the Atlantic Ocean to the Pacific Ocean. This belief was fueled by a combination of religious, economic, and political motives.

To get a comprehensive understanding of how the concept evolved and the reasoning behind it, you can follow these steps:

1. Research the historical background: Study the history of the United States during the 19th century, including events such as the Louisiana Purchase, the Lewis and Clark expedition, and the westward expansion in general.

2. Look into political ideologies: Investigate the political debates and ideologies of the time, especially those around expansionism and nationalism. This includes reading about politicians such as John L. O'Sullivan, who coined the term "Manifest Destiny" in 1845.

3. Explore economic motives: Understand the economic factors that contributed to the idea of territorial expansion. This involves examining concepts such as trade, resources, and the desire for economic prosperity.

4. Analyze cultural and religious influences: Examine the role of cultural and religious beliefs in shaping the ideology of Manifest Destiny. This includes understanding the influence of Protestant Christianity and the notion of American exceptionalism.

By researching and considering these various aspects, you will gain a thorough understanding of the concept of Manifest Destiny and its moral obligation for territorial expansion.