No first use

No first use (NFU) refers to a pledge or a policy by a nuclear power not to use nuclear weapons as a means of warfare unless first attacked by an adversary using nuclear weapons. This concept is also applied to chemical and biological warfare in case of the NFU policy of India.
China declared its NFU policy in 1964, and has since maintained this policy.
India declared its NFU policy in 1998, and has since maintained this policy.
NATO has repeatedly rejected calls for adopting NFU policy, arguing that pre-emptive nuclear strike is a key option, in order to have a credible deterrent that could compensate for the overwhelming conventional weapon superiority enjoyed by the Soviet Army in the Eurasian land mass. In 1993, Russia dropped a pledge against first use of nuclear weapons made in 1982 by Leonid Brezhnev. In 2000, a Russian military doctrine stated that Russia reserves the right to use nuclear weapons "in response to a large-scale conventional aggression".
Countries pledging no-first-use.
China.
China became the first nation to propose and pledge NFU policy when it first gained nuclear capabilities in 1964, stating "not to be the first to use nuclear weapons at any time or under any circumstances." During the Cold War, China decided to keep the size of its nuclear arsenal small, rather than compete in an international arms race with the United States and the Soviet Union.<ref name="S/1995/265"></ref> China has repeatedly reaffirmed its no-first-use policy in recent years, doing so in 2005, 2008, 2009 and again in 2011. China has also consistently called on the United States to adopt a no-first-use policy, to reach an NFU agreement bilaterally with China, and to conclude an NFU agreement among the five nuclear weapon states. The United States has repeatedly refused these calls.
India.
India first adopted a "no first use" policy after its second nuclear tests, Pokhran-II, in 1998. In August 1999, the Indian government released a draft of the doctrine which asserts that nuclear weapons are solely for deterrence and that India will pursue a policy of "retaliation only". The document also maintains that India "will not be the first to initiate a nuclear first strike, but will respond with punitive retaliation should deterrence fail" and that decisions to authorise the use of nuclear weapons would be made by the prime minister or his 'designated successor(s)'. According to the National Research Development Corporation, despite the escalation of tensions between India and Pakistan in 2001–2002, India remained committed to its nuclear no-first-use policy. India is in the process of developing a nuclear doctrine based on "credible minimum deterrence".
In a speech at the National Defence College on October 21, 2010 by India's National Security Advisor, Shivshankar Menon, the wording was changed from "no first use" to "no first use against non-nuclear weapon states", but some argued that it was not a substantive change but "an innocent typographical or lexical error in the text of the speech." Prime Minister Modi has, before the recent general elections, reiterated commitment to a no first use policy. In April 2013, Shyam Saran, convener of the National Security Advisory Board, affirmed that regardless of the size of a nuclear attack against India, be it a tactical nuclear weapon or a strategic nuclear weapon, India will retaliate massively. That was in response to reports that Pakistan had developed a tactical battlefield nuclear weapon in an attempt to supposedly nullify an Indian "no first use" retaliatory doctrine. On 10 November 2016, the Indian Defence Minister Manohar Parrikar questioned the no first use policy of India and asked why should India “bind” itself when it is a “responsible nuclear power.” He clarified that it was his personal opinion.
Indian Defence Minister Rajnath Singh, speaking on the death anniversary of former Prime Minister Atal Bihari Vajpayee on 16 August 2019, said that India's no first use policy might change depending upon the "circumstances." Vajpayee's government conducted the Pokhran-II nuclear tests in 1998.
Countries against no-first-use policy.
Pakistan, Russia, United Kingdom, United States, and France say that they will use nuclear weapons against either nuclear or non-nuclear states only in the case of invasion or other attack against their territory or against one of their allies. Historically, NATO military strategy, taking into account the numerical superiority of Warsaw Pact conventional forces, assumed that tactical nuclear weapons would have to be used to defeat a Soviet invasion.
At the 16th NATO summit in April 1999, Germany proposed that NATO adopt a no-first-use policy, but the proposal was rejected.
Russia.
Russia describes its entire military doctrine as defensive military doctrine.
With regard to nuclear weapons specifically, Russia reserves the right to use nuclear weapons:
The new military doctrine of 2014 does not depart from this stance.
United Kingdom.
In March 2002, the Secretary of State for Defence Geoff Hoon stated that the UK was prepared to use nuclear weapons against "rogue states" such as Iraq if they ever used "weapons of mass destruction" against British troops in the field. This policy was restated in February 2003. In April 2017 Defence Secretary Michael Fallon confirmed that the UK would use nuclear weapons in a "pre-emptive initial strike" in "the most extreme circumstances". Fallon stated in a parliamentary answer that the UK has neither a 'first use' or 'no first use' in its nuclear weapon policy so that its adversaries would not know when the UK would launch nuclear strikes.
United States.
The United States has refused to adopt a no first use policy and says that it "reserves the right to use" nuclear weapons first in the case of conflict. The US doctrine for the use of nuclear weapons was revised most recently in the Nuclear Posture Review, released April 6, 2010. The 2010 Nuclear Posture review reduces the role of U.S. nuclear weapons, "The fundamental role of U.S. nuclear weapons, which will continue as long as nuclear weapons exist, is to deter nuclear attack on the United States, our allies, and partners." The U.S. doctrine also includes the following assurance to other states: "The United States will not use or threaten to use nuclear weapons against non-nuclear weapons states that are party to the NPT and in compliance with their nuclear non-proliferation obligations."
For states eligible for the assurance, the United States would not use nuclear weapons in response to a chemical or biological attack but states that those responsible for such an attack would be held accountable and would face the prospect of a devastating conventional military response. Even for states that are not eligible for the assurance, the United States would consider the use of nuclear weapons only in extreme circumstances to defend the vital interests of the United States or its allies and partners. The Nuclear Posture Review also notes, "It is in the U.S. interest and that of all other nations that the nearly 65-year record of nuclear non-use be extended forever."
This supersedes the doctrine of the George W. Bush administration set forth in "Doctrine for Joint Nuclear Operations" and written under the direction of Air Force General chairman of the Joint Chiefs of Staff. The new doctrine envisions commanders requesting presidential approval to use nuclear weapons to preempt an attack by a nation or a terrorist group using weapons of mass destruction. The draft also includes the option of using nuclear weapons to destroy known enemy stockpiles of nuclear, biological, or chemical weapons.
In August 2016, President Barack Obama reportedly considered adopting a 'No First Use' policy. Obama was persuaded by several Cabinet officials that 'No First Use' would rattle U.S. allies and decided not to take up the policy.
In 2017, there were efforts to either require congressional approval for a pre-emptive nuclear strike or to ban it altogether and impose an NFU policy.
Pakistan.
Pakistan's Foreign Minister Shamshad Ahmad warned that if Pakistan is ever invaded or attacked, it will use "any weapon in its arsenal" to defend itself.
Pakistan refuses to adopt a no first use doctrine and indicates that it would launch nuclear weapons even if the other side did not use such weapons first. Pakistan's asymmetric nuclear posture has significant influence on India's ability to retaliate, as shown in 2001 and 2008 crises, when non-state actors carried out deadly terrorist attacks on India, only to be met with a relatively subdued response from India. A military spokesperson stated that "Pakistan's threat of nuclear first-use deterred India from seriously considering conventional military strikes."
Pakistan's National Security Advisor Sartaj Aziz defended the policy of first use. Aziz stated that Pakistan's first use doctrine is entirely deterrent in nature. He explained that it was effective after the 2001 Indian Parliament attack and argued that if Pakistan had a no first use policy, there would have been a major war between the two countries.
Israel.
Although Israel does not officially confirm or deny having nuclear weapons, the country is widely believed to be in possession of them. Its continued ambiguous stance puts it in a difficult position since to issue a statement pledging 'no first use' would confirm their possession of nuclear weapons.
Israel has said that it "would not be the first country in the Middle East to formally introduce nuclear weapons into the region."
If Israel's very existence is threatened, some speculate that Israel would use a "Samson Option," a "last resort" deterrence strategy of massive retaliation with nuclear weapons, should the State of Israel be substantially damaged and/or near destruction. According to Israeli historian Avner Cohen, Israel's policy on nuclear weapons, which was set down in 1966, revolves around four "red lines" which could lead to an Israeli nuclear response:
North Korea.
North Korea's stated policy position is that nuclear weapons "will never be abused or used as a means for preemptive strike", but if there is an "attempt to have recourse to military force against us" North Korea may use their "most powerful offensive strength in advance to punish them".