Strategic Stability: When either of two adversaries can be assured of destroying the other, even if attacked first; if this is in doubt, the situation is described as strategically unstable.

Crisis Stability: When there is little or no incentive for either adversary to attack the other first in a crisis; if there is an incentive to attack first, the situation is described as crisis unstable.

Arms Race Stability: When there is no incentive for either adversary to deploy more weapons; if there is an incentive, the situation is described as arms race unstable.

International War: Large-scale armed conflict between the military forces of two or more States.

Civil War: Large-scale armed conflict of adversaries within a State.

Pre-emptive War: A war initiated to disrupt an attack that is already underway or is imminent. Pre-emptive war is permissable under International Law only if (1) an attack is imminent, (2) there is no other way of preventing or stopping the attack, and (3) the pre-emptive action is proportionate to the threat.

Preventive War: A war initiated in the absence of an imminent attack or without pursuing all other available means, which has the goal of preventing an adversary from attacking at some future time. Preventive war is a violation of International Law.

Limited War: Less than all-out warfare; use of only a fraction of available warheads in a deliberate manner; sometimes called ''sending signals with pain''.

First Strike: Attacking an adversary before the adversary attacks you. Variants are ''first use'', the 1950s through 1970s NATO policy of using nuclear weapons first if a Soviet conventional attack were to appear to be overwhelming NATO conventional forces, ''pre-emption'' (striking first when an attack is imminent or underway an there is no other way of preventing or stopping the attack), and ''preventive attack'' (striking first when no attack is underway or imminent but an attack could become possible in the future). See the definitions of preemptive war and preventive war.

Second Strike: Attacking the adversary after he attacks you; often called a ''retaliatory strike''.

Counterforce Targeting: Planning to attack the military forces and command structure of the adversary. Such a policy creates an incentive to deploy more, and more accurate, weapons. A variant of NUTS (see below). According to most analyses, there would be little difference in the end result of a nuclear war conducted using counterforce (see below) or countervalue targeting.

Countervalue Targeting: Planning to attack the cities and industries of the adversary.

Massive Retaliation: The 1954–1962 U.S. policy of responding to even a small-scale Soviet conventional attack on the U.S. or an ally by an all-out nuclear attack on the Soviet Union.

Flexible Response: The 1960s NATO policy of responding to attack by choosing among a variety of options (weapons, targets, timing), including use of nuclear weapons to counter a conventional attack (''first use'').

Nuclear Weapon Utilization Strategy (NUTS): The strategy of using a full arsenal of 12,000 or more warheads to destroy all conceivable targets in another country.

Warfighting Posture: A nuclear policy of emphasizing the ability to launch attacks quickly on the leadership and nuclear forces of an adversary and, if necessary, to continue attacks for days, weeks, or months. Major elements of this policy that are usually cited include ''flexibility'', ''escalation control'', ''endurance of forces and communications'', a ''large menu of pre-programmed targets'', and ''maintenance of reserve forces''.

War-Winning Posture: A nuclear force posture based on the assumption that even in an all-out nuclear war, ''victory is possible''; current euphemisms for victory include ''the ability to prevail'' and ''the ability to end hostilities on terms favorable to us''.

Assured Destruction Capability: Situation when a country has deployed secure retaliatory forces sufficient in number to be able to destroy a large fraction of the industry and kill a large fraction of the population of the adversary, even after absorbing a first strike. The emphasis is on the security of the forces and their sufficiency for deterrence.

Mutual Assured Destruction (MAD): The situation when two adversaries have deployed a sufficient number of protected nuclear weapons to be able to destroy the other after absorbing a first strike.

Minimal Deterrence: A policy of deterring nuclear attack on oneself by deploying only enough nuclear forces to be able to destroy an appreciable fraction of the population and industry of any attacker after being subjected to an attack. The emphasis of this policy is on avoiding an arms race while still deterring nuclear attack. Defense Secretary Robert McNamara reportedly considered 400 deliverable equivalent megatons sufficient to deter the Soviet Union from attacking the U.S.

Proliferation: Increase in the number of nuclear weapons; deployment of more or new types of nuclear weapons by states that already have them is referred to as ''vertical'' proliferation whereas the spread of nuclear weapons to previously non-nuclear-weapon states is sometimes referred to as ''horizontal'' proliferation.

Strategic: 1. (when applied to bombing or weapons generally) Done or for use against industrial areas and communication centers of enemy territory as a long-term military objective. 2. (when applied to U.S. and Soviet/Russian nuclear weapons) Weapons or warfare that involves the homelands of the adversaries.

Tactical: 1. (when applied to bombing or weapons generally) Done or for use in immediate support of military or naval operations. 2. (when applied to U.S. and Soviet/Russian nuclear weapons) Weapons or warfare that does not involve the homelands of the adversaries.