One of the most fundamental features, and perhaps the most profound, of the world order today is the way it is organized into sovereign states. International Law as expressed in treaties only recognizes sovereign states as capable of executing and implementing treaties.
In terms of the laws of war, a neutral state is one which is not taking part in a war. Early treaties dealing with neutrality are the 1907 Hague Conventions and the 1928 Havana Convention on maritime neutrality. For example the 1907 Hague Convention V states "Article 1 - The territory of neutral powers is inviolable. Article 2 - Belligerents are forbidden to move troops or convoys of either munitions of war or supplies across the territory of a neutral power".
Convention XIII states "Belligerents are bound to respect the sovereign rights of neutral Powers and to abstain, in neutral territory or neutral waters, from any act which would if knowingly permitted by any Power, constitute a violation of neutrality".
The traditional laws of war relating to neutral powers are based in part upon a duty to respect the expression of a sovereign state to opt out of a war. The principle of sovereign equality is inherent in the United Nations Charter, and Members of the United Nations ". . .shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations".
Traditionally, when the territorial rights of a neutral power are violated, it has a right to demand reparation, which it may or may not do so, but when the rights are violated by a belligerent in wartime there is a duty to try and prevent violation and demand reparation if appropriate in order to remain impartial. It is abundantly clear that in the event of nuclear war affecting neutral powers, reparations would be ineffective, if not irrelevant.
A specific international assertion of sovereignty by non-nuclear powers wishing to be free from the effects of nuclear weapons can be found in the Latin-America Nuclear-Free Zone Treaty.
Nuclear testing as part of the development and deployment of nuclear weapons systems has dispersed radioactivity generally affecting nuclear and non-nuclear powers alike.
The nuclear weapons states are unable to discriminate between belligerents and non-belligerents in all effects of the use of nuclear weapons. It is a strange proposition indeed that states may indiscriminately destroy non-belligerents in furtherance of a nuclear weapons policy, particularly where those non-belligerents have declared their neutrality with respect to any nuclear conflict. Such a proposition in an outrageous breach of established laws and customs of war, constitutes a grave intention to wage aggressive war, and is a crime against humanity.
In evidence was the proposition that under the present circumstances of an essentially illegal international security system by nuclear powers, neutral powers have a duty to fulfil the universal entitlement to stop the commission of crimes of State by giving a legal competence to act against such unlawfulness. As a minimum, non-nuclear states should establish and encourage widespread adherence to, a treaty based upon a formal consensus of the illegality of nuclear weapons plans, construction, testing, deployment and possible use.
It is instructive to note that United Nations General Assembly Resolution 38/68 on the Non-use of Nuclear Weapons and Prevention of Nuclear War of 15th December 1983 was passed with 141 in favour, 0 against and 6 abstentions, to the effect that the General Assembly "Recommends that the Conference on Disarmament should continue negotiation with a view to reaching early agreement and concluding effective international arrangements to assure non-nuclear weapon states against the use or threat of use of nuclear weapons, taking into account the widespread support for the conclusion of an international convention and giving consideration to any other proposals designed to secure the same objective"15.
15 Summary taken from the SIPRI Yearbook 1984.