The Nuclear doctrine of State of Pakistan (otherwise referred as Option-enhancing Policy (OeP); or simply: Nuclear doctrine;), is a theoretical concept of military strategy that promotes the deterrence by guaranteeing an immediate "massive retaliation" to an aggressive attacks against the state. This doctrine obtained various mathematical models of the "Game theory" for its effective operational use; it is consisted of numbers of set of strict principles (roughly based on Game theory, Nash equilibrium and parts of the Decision theory), rules, regulations, and comprehensive instructions for the operational employment or non-operational employment of atomic weapons and other strategic systems associated with those weapons.
Persuasion for Effect 
The doctrine is divided into four different threshold before the weapons are being operationally charged during the conventional and nuclear war with an aggressor state. In an event of war, for instance the war between India and Pakistan, the Indian Armed Forces physical and numerical superiority and large stock of conventional armory and weaponry is most likely to overwhelm Pakistan. Therefore, in a deteriorating situation, when an Indian military aggression is more likely to penetrate through Pakistan's defenses (or has already breached the main defense line causing a major setback to the defense) which cannot be restored by conventional means, the government would be left with no other option except to use nuclear weapons to stabilize the situation, as part of the first strike.
The rationale behind the doctrine is to prevent India from any military intervention (both convention and surgical) that would lead to the disintegration of the country, as it did in 1971 (see Indo-Pakistani war of 1971). The South Asian affairs expert, Professor Stephen P. Cohen further elaborates and term the strategy of Pakistan as "Option-enhancing Policy". According to the sources, the doctrine advances and entails a stage-by-stage level of advancement in which the nuclear threat is increased at each step to deter India (or any aggressor state) from attacking, as it is listed below:.
- A public or private warning.
- A demonstration atomic test of a small atomic device on its own soil (preferably at weapon-testing laboratories).
- The use of (a) nuclear weapon(s) on Pakistan's soil against foreign (or India) attacking forces.
- The use of (a) nuclear weapon(s) against critical but purely military targets on foreign (or Indian) soil, probably in thinly populated areas in the desert or semi-desert, causing the least collateral damage.
Levels of Threshold 
The doctrine is not the part of the Minimum Credible Deterrence principle of Pakistan, however, the doctrine is integrated the nuclear dimension into its defence principle. According to the sources (after being obtained from Pakistan's nuclear command authority) published by the International Institute for Strategic Studies (IISS), the definition of four potential thresholds has been refined in the form of four thresholds which were first mentioned by officials at the nuclear command authority in late 2001.
- Spatial Threshold—— The armed and military penetration of Indian Armed Forces into Pakistan on large scale may elicit a nuclearize massive retaliation, if and only if the Pakistan Army is unable to stop such intervention. For instance, many analysts, including some Indians, believe that the Indus Valley— the "lifeline" of Pakistan— is one of many other "red lines" that Indian forces should not cross. The capture of key objectives in this crucial northeast–southwest axis might well provoke nuclear retaliation by Pakistan.
- Military Threshold—— The complete knockout or comprehensive destruction of a large part of Pakistan Armed Forces, particularly and most importantly the Pakistan Air Force (PAF), could lead to a quick nuclear response if Islamabad believed that it was losing the cohesiveness of its defence and feared imminent defeat. A senior ranking PAF officer maintained that "orders given to PAF (and its missile command) are identical to the guidelines given to the NATO commanders during the Cold war crises. This criterion is even more important for the Pakistan Armed Forces because of its critical role in maintaining the country’s stability. As noted above, an attack on a nuclear installation has also been posited as a threshold. According to PAF, this level of threshold also included the chemical or biological weapons attack against Pakistan, would also respond to massive retaliation.
- Economic Threshold—— This level implicitly and explicitly refers for the countermeasure operations of Pakistan Navy. The economic strangulation and economic blackade is also a potential threat to Pakistan, in which if Pakistan Navy is unable to counter it effectively (for example, see operations: Trident and Python in 1971). This primarily refers to a potential Indian Navy blockade of Sindh Province and coastal cities of Balochistan Province, or the stopping of the Indus water flow. It could also refer to the capture of vital arteries such as the Indus.
- Political Threshold—— Finally, Pakistan's geostrategist, game theorists and political strategists and planners suggest that a destabilization of the country by India could also be a nuclear threshold if Islamabad has credible proves to believe that the integrity of the country were at stake. Stated scenarios are political destabilization or large-scale internal destabilization in which if Pakistan Marines (along with other paramilitary command) are unable to stabilized it effectively. One example would be encouraging the breakaway of one or more Pakistan's provinces. (for example, see: the Bangladesh Liberation War)
Alternate substitution 
In 1998, Foreign secretary Shamshad Ahmad that "Pakistan's policy implies that it will not only use nuclear weapons in a retaliatory strike, it is also ready to take the lead and use nuclear weapons first to counter Indian conventional aggression.".
- Lodhi, Lieutenant-General (retired) FS (April 1999). "Pakistan’s Nuclear Doctrine". Lieutenant-General Sardar FS Lodi, former operationals commander of Pakistan's joint special forces command. Islamabad, Pakistan: Defence Journal of Pakistan. p. 1. Retrieved 19 July 2012. More than one of
- The Military Balance 2010, p. 367, International Institute for Strategic Studies (London, 2010).
- ISS. "IISS: Nuclear policy". International Institute for Strategic Studies. International Institute for Strategic Studies. Retrieved 19 July 2012. More than one of
- Chakma, Bhumitra, Pakistan’s Nuclear Doctrine and Command and Control system; Dilemmas of Small Nuclear Forces in the Second Atomic Age.
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