This dissertation examines India’s foreign policy responses to the nuclear programs of fifteen states, with particular in-depth analysis of Iran and North Korea. To understand India’s positions across different cases, this study categorizes responses into four categories: material support, rhetorical support, rhetorical opposition, and material opposition. This study uses qualitative methods, including process tracing and comparative case studies, to show how India’s stance shifts across regions in line with its core interests. The findings reveal that India's responses are guided by economic interests and security concerns rather than normative principles of non-proliferation and disarmament. India rhetorically and materially supported the nuclear ambitions of Iran, Iraq, Libya, and Egypt due to economic interests, which were often rooted in energy security concerns. In contrast, it opposed the nuclear weapons programs of China and Pakistan, which directly threatened Indian national security. India also publicly opposed North Korea's nuclear weapons program, citing security concerns; however, these concerns emerged only after North Korea’s missile technology transfer to Pakistan. This study found that the perceived threat was limited, and India’s opposition was largely rhetorical. This study further finds that India’s alignment with the U.S. is mainly symbolic, with cooperation occurring only when it does not compromise India’s core interests. This study finds that India consistently offered rhetorical and material support for Iran’s nuclear ambitions but, under U.S. pressure, voted three times in the 2000s for IAEA resolutions against Iran for non-compliance with nuclear safeguards. Although these votes were more symbolic than substantive, they were intended mainly to align with the United States amid emerging Indo-U.S. civil nuclear cooperation. Nonetheless, during that period, India maintained covert cooperation with Iran, reflecting its priority in securing energy supplies. Similarly, India opposed the nuclear programs of North Korea, Brazil, and Argentina, aligning with the U.S. position, where the strategic costs of opposition were minimal. Finally, the study examines a shift in India’s public stance before and after 1968. It finds that although India’s responses remained driven by economic interests and security concerns, the justification for those positions evolved from advocating global nonproliferation to favoring selective proliferation guided by strategic interests.