India conducted five nuclear tests in May 1998, including one with an explosive yield of 43 kilotons - more than twice bigger than bomb dropped on Hiroshima in 1945.
India first decided to build its own nuclear weapons after China began nuclear tests in the mid-1960s. Two primary factors drive India's nuclear program: the need to balance China's growing nuclear arsenal and the ongoing conflict with Pakistan over Kashmir. The Indian government released a proposed nuclear doctrine in 1999. This document calls for the use of nuclear weapons only in response to a nuclear attack - in other words a no first use policy - and says that ultimately, India's nuclear forces will be based in a triad of aircraft, mobile land-based missiles and sea-based forces. The doctrine states that India intends, through a combination of redundant systems, mobility, dispersion and deception, to heighten the survivability of its nuclear arsenal. Despite its ambition to deploy a nuclear triad, today India can deliver nuclear weapons only by missile or aircraft.

India has two types of missiles: the Prithvi and the Agni, each of which has several variants. The Prithvi missiles have ranges under 500 kilometers and are liquid-fueled. In January 2002, India test fired a solid-fuel Agni missile. With a range of 700 kilometers, it bridges a gap between shorter-range Prithvi missiles and longer-range variants of the Agni. Versions of the Agni with ranges up to 5,000 kilometers are being developed. Though India seeks nuclear self-sufficiency, its ballistic missile programs are largely dependent on Russian components and expertise. India is also likely to develop a global positioning system to upgrade its missile guidance systems.

India has several aircraft that could be outfitted to deliver nuclear bombs. It is not clear which, if any, have been modified for nuclear delivery. India's 147 MiG-27s and 88 Jaguars would require little or no modification to deliver nuclear weapons. In addition, India has 150 Mig-21 fighters, 64 MiG-29s, and 36 Mirage 2000s, which could all be upgraded to carry nuclear weapons.

Indian attempts to complete the submarine-based third of its nuclear triad have been beset by technical difficulties, and success on this front remains a long way off.