India's journey into nuclear development began in 1944 when physicist Homi Jehangir Bhabha founded the Tata Institute of Fundamental Research. After gaining independence from the British Empire in 1947, Prime Minister Jawaharlal Nehru authorized the development of a nuclear program under Bhabha's direction, focusing initially on peaceful development as per the Atomic Energy Act of 1948. India actively participated in the formation of the Nuclear Non-Proliferation Treaty but ultimately chose not to sign it.

In 1954, Bhabha shifted the nuclear program towards weapons design and production, establishing significant projects like the Trombay Atomic Energy Establishment and the Department of Atomic Energy. By 1958, this program had secured a significant portion of the defense budget. India also entered into agreements with Canada and the United States under the Atoms for Peace program, receiving the CIRUS research reactor for peaceful purposes. However, India chose to develop its indigenous nuclear fuel cycle.

Under Project Phoenix, India built a reprocessing plant by 1964 to match the production capacity of CIRUS. The 1960s marked a pivotal shift towards nuclear weapons production under Bhabha and, after his death, Raja Ramanna. The nuclear program faced challenges during the Sino-Indian War in 1962, leading India to perceive the Soviet Union as an unreliable ally and reinforcing its commitment to developing a nuclear deterrent.

The nuclear weapons development accelerated under Prime Minister Indira Gandhi in the late 1960s, with significant contributions from scientists like Homi Sethna and P. K. Iyengar. The program focused on plutonium rather than uranium for weapons development. In 1974, India conducted its first nuclear test, codenamed "Smiling Buddha", under extreme secrecy and with limited involvement of military personnel.

The test, initially declared as a peaceful nuclear explosion, had significant domestic and international repercussions. It bolstered Indira Gandhi's popularity within India and led to civilian honors for key project members. However, internationally, it prompted the formation of the Nuclear Suppliers Group to control nuclear proliferation and affected India's nuclear relations with countries like Canada and the United States. The test also had profound implications for India's relationship with Pakistan, heightening regional nuclear tensions.