Bhutan is located in between two regional powers that have significant military force. Due to its location, Bhutan serves as a barrier to further Chinese aggression to India's "chicken neck" area of Siliguri Corridor. Because of this, India seeks to have a strong relationship with Bhutan. This can be seen from recent current events in Bhutan from 2017: Chinese forces were building roads in a disputed border area between Bhutan and China. According to the Sigur Center for Asian Studies from George Washington University's Justin Seledyn, "The standoff in Bhutan’s disputed Doklam region this summer occurred near the tri-junction of India, China, and Bhutan, and just east of the Sikkim border." (Seledyn 2017, p. 3). This was due to Chinese forces entering the area and beginning construction of a road, leading Bhutanese forces to request China leave the area with backup assistance from Indian forces (Seledyn 2017, p. 3). As seen, India serves as a protector of Bhutan.
Seledyn spoke with India's former Foreign Secretary, Ambassador Nirupama Rao, about India's relationship with Bhutan, "Ambassador Rao made note of the strong bilateral relationship between India and neighboring Bhutan, calling it in many ways a “model relationship.” Much of this relationship is also based on trade and economic prosperity with Bhutan exporting the majority of its hydropower to India in exchange for a multitude of goods and services, spanning from infrastructural enhancements to daily staple products.
Following China’s adoption of communism and its incorporation of Tibet, Bhutan distanced itself from its northern neighbor. Today, India and Bhutan enjoy strong political, development, economic, and military relations." (Seledyn 2017, p. 3). Bhutan relies on India for many interests. Due to the threat posed by China with the annexation of Tibet, with which Bhutan has a rich spiritual and cultural history, Bhutan is cautious with its Northern neighbor and seeks a strong bond with its Southern neighbor.
Seledyn, Justin. "The Face-Off in Doklam: Interpreting India-China Relations." Sigur Center for Asian Studies, George Washington University. October 2017. Accessed December 11, 2018 from https://www2.gwu.edu/~sigur/assets/Docs/publications/asiareports/AsiaReport-37-v6.pdf