About this topic
The law of neutrality explains how a state that stays out of a war between other states is protected, and what that state must do in return. One historical episode contains almost the whole subject.
Les Verrières, 1871: On 1 February 1871, a beaten French army stood in the snow at Les Verrières, a small village on the Swiss border. More than 80,000 cold and hungry soldiers wanted to cross into Switzerland. Switzerland let them in, fed them and cared for their wounded. But at the border the soldiers had to lay down their weapons, and the whole army stayed in Switzerland until the fighting was over. Why open the door but take away the guns? The answer is the law of neutrality (see the duty of internment below).
Three problems to keep in mind
- A fighter jet of a country at war runs low on fuel, lands in a neutral country and asks for fuel to fly home.
- A private factory in a neutral country sells drones to one of the warring states, and the neutral government does nothing.
- A neutral country lets an ambulance convoy of wounded soldiers cross its territory, but two armed soldiers ride along as guards.
The answers are given at the end of these notes.
Meaning of neutrality
Neutrality is the legal status of a state that is not taking part in an international armed conflict between other states. The states that are fighting are called belligerents.
The law of neutrality governs the relationship between belligerents and neutral states. It therefore sits right next to International Humanitarian Law (IHL).
| International Humanitarian Law | Law of neutrality |
|---|---|
| Tells the fighting states how to fight. | Tells the fighting states where they cannot fight, and tells outsiders how to remain outside. |
Neutrality and non-alignment
Students in India often confuse neutrality with non-alignment. They are different things.
| Point | Non-alignment | Neutrality |
|---|---|---|
| Nature | A foreign policy | A legal status |
| When it operates | Chosen in peacetime | Arises during a particular war |
| Content | The country stays away from military blocs | Carries legal rights and legal duties |
A state can be non-aligned and still go to war, as India itself did in 1971. Non-alignment is a policy; neutrality is a legal status in a particular war.
How neutrality arises
Neutrality needs no ceremony. A state may declare it formally, or it may simply stay out of the war.
Non-belligerency: the grey zone
A state that does not fight but openly backs one side is usually called non-belligerent rather than neutral.
Before entering the Second World War, the United States openly supplied Britain under the Lend-Lease Act of 1941. It was not fighting, but it was openly backing one side.
Sources of the law of neutrality
The rules are not found in a single modern code. The core is still found in two treaties adopted at The Hague on 18 October 1907:
| Treaty | Subject |
|---|---|
| Hague Convention V (1907) | Neutral powers and persons in war on land |
| Hague Convention XIII (1907) | Neutral powers in naval war |
Both Conventions contain a clause saying that they apply only if all the belligerents are parties to them. But their rules are now largely accepted as customary international law, so they matter well beyond that limit.
Further rules were added by:
- the Geneva Conventions of 1949; and
- Additional Protocol I of 1977.
Exam tip: the core sources are Hague Convention V (land) and Hague Convention XIII (naval) of 18 October 1907. Their own clause limits them to wars where all belligerents are parties, but their rules now largely bind as customary international law. The Geneva Conventions of 1949 and Additional Protocol I of 1977 add further rules.
Neutrality as a bargain
Neutrality is a bargain. The neutral state receives a shield, and in return it gives a promise. The shield keeps the war away from its territory. The promise assures both sides that its territory will not help either of them win.
| Half of the bargain | What it does | What it contains |
|---|---|---|
| The shield (protection of the neutral) | Keeps the war away from neutral territory | Inviolability of territory; protection of neutral persons; no troops, recruiters or military radio stations on neutral soil |
| The promise (duties of the neutral) | Assures both sides that neutral territory will not help either of them win | Abstention, prevention, impartiality and internment |
The shield: protection of the neutral state
Inviolability of neutral territory (Article 1, Hague Convention V)
"The territory of neutral Powers is inviolable."
Inviolable means that no one may break into it. The protected territory covers:
- the land;
- the territorial sea, which may extend up to 12 nautical miles from the coast; and
- the airspace above both.
Neutral persons (Articles 16 and 17, Hague Convention V)
The shield covers people too. Article 16 says: "The nationals of a State which is not taking part in the war are considered as neutrals."
But a person can throw this protection away. Under Article 17, a neutral cannot avail himself of his neutrality:
- Clause (a): "If he commits hostile acts against a belligerent"; or
- Clause (b): "If he commits acts in favor of a belligerent, particularly if he voluntarily enlists in the ranks of the armed force of one of the parties."
A neutral engineer who joins one side's army loses the protection of neutrality.
Article 17 adds a fairness limit: "the neutral shall not be more severely treated by the belligerent as against whom he has abandoned his neutrality than a national of the other belligerent State could be for the same act."
A neutral who abandons neutrality loses its protection, but may not be treated more harshly than a national of the enemy belligerent state would be for the same act.
Boots, recruiters and radios (Articles 2 to 4, Hague Convention V)
The shield also binds the belligerents to keep three things out of neutral territory: boots, recruiters and radios.
Boots: armies (Article 2)
"Belligerents are forbidden to move troops or convoys of either munitions of war or supplies across the territory of a neutral Power."
Recruiters (Article 4)
"Corps of combatants cannot be formed nor recruiting agencies opened on the territory of a neutral Power to assist the belligerents."
Radios: military communication (Article 3)
Belligerents are forbidden:
- Clause (a): to "Erect on the territory of a neutral Power a wireless telegraphy station or other apparatus for the purpose of communicating with belligerent forces on land or sea"; and
- Clause (b): to "Use any installation of this kind established by them before the war on the territory of a neutral Power for purely military purposes, and which has not been opened for the service of public messages."
A secret relay station guiding one army's operations has no place on neutral soil.
| Kept out | Meaning | Provision (Hague Convention V) |
|---|---|---|
| Boots | Movement of troops, or convoys of munitions or supplies, across neutral territory | Article 2 |
| Radios | Wireless stations or apparatus for military communication with belligerent forces | Article 3 |
| Recruiters | Forming corps of combatants or opening recruiting agencies | Article 4 |
The promise: duties of the neutral state
The neutral state's promise can be put in four sentences, spoken to both belligerents:
| Promise | Legal duty | Main provisions |
|---|---|---|
| "I will not arm you." | Duty of abstention | Article 6, Hague Convention XIII; Article 7, Hague Convention V |
| "I will not let you use my land." | Duty of prevention | Articles 5 and 6, Hague Convention V; Article 8, Hague Convention XIII |
| "I will not favour either of you." | Duty of impartiality | Article 9, Hague Convention V |
| "If you cross my border, I will hold you." | Duty of internment | Articles 11 to 13, Hague Convention V |
1. Duty of abstention: "I will not arm you"
Article 6 of Hague Convention XIII says:
"The supply, in any manner, directly or indirectly, by a neutral Power to a belligerent Power, of war-ships, ammunition, or war material of any kind whatever, is forbidden."
Notice the words "by a neutral Power". The duty binds the government. Private business is treated differently. Article 7 of Hague Convention V says:
"A neutral Power is not called upon to prevent the export or transport, on behalf of one or other of the belligerents, of arms, munitions of war, or, in general, of anything which can be of use to an army or a fleet."
| Supply by the neutral government | Export by private traders |
|---|---|
| Forbidden: warships, ammunition or war material of any kind, directly or indirectly (Article 6, Hague Convention XIII) | The neutral state is not called upon to prevent it (Article 7, Hague Convention V) |
The state's own arsenal is closed, but the law of neutrality does not automatically shut down its private traders.
2. Duty of prevention: "I will not let you use my land"
Article 5 of Hague Convention V says:
"A neutral Power must not allow any of the acts referred to in Articles 2 to 4 to occur on its territory."
So when boots, recruiters or radios try to come in, the neutral state must stop them. But under Article 6, the neutral state is not responsible merely because individuals cross the border separately to offer their services to one side.
An organised recruiting office on neutral territory is a breach of neutrality. A lone volunteer buying a train ticket to join one side is not.
Due diligence: the lesson from the sea
The Alabama arbitration (United States and Britain) (1872): During the American Civil War, a ship later named the Alabama was built in a British shipyard near Liverpool for the Confederate side. It sailed out unarmed, received its guns and crew at sea, and then destroyed or captured dozens of Union merchant ships, until it was sunk off the French coast in 1864. Neutral Britain said it had broken no law. By the Treaty of Washington of 1871, the two countries sent the dispute to arbitration under rules requiring a neutral government to use due diligence to stop such ships. Held: On 14 September 1872, the tribunal at Geneva held that Britain had failed in that duty, and awarded the United States 15.5 million dollars in gold. Principle: A neutral government must use due diligence to stop ships being fitted out or armed within its jurisdiction for a belligerent. A neutral state cannot close its eyes and call that neutrality.
The principle was later written into Article 8 of Hague Convention XIII:
"A neutral Government is bound to employ the means at its disposal to prevent the fitting out or arming of any vessel within its jurisdiction which it has reason to believe is intended to cruise, or engage in hostile operations, against a Power with which that Government is at peace."
3. Duty of impartiality: "I will not favour either of you"
The duty of impartiality is often misunderstood.
A cricket umpire is not impartial because both teams end the match with the same score. The umpire is impartial because the same rules are applied to both teams. Neutrality works the same way.
Article 9 of Hague Convention V says:
"Every measure of restriction or prohibition taken by a neutral Power in regard to the matters referred to in Articles 7 and 8 must be impartially applied by it to both belligerents."
So if a neutral state bans the export of weapons, the ban must cover both sides.
Impartiality means the same rules for both belligerents, not equal results for both.
Courant normal: ordinary pre-war trade
A neutral state is not required to redesign its economy the day a war begins. On the traditional view, ordinary commerce at its pre-war level, often called the courant normal, does not breach neutrality. The problem begins when the neutral state reshapes its conduct to help one side win.
A neutral country that has exported tea and textiles to one warring state for decades may keep up that normal flow.
4. Duty of internment: "If you cross my border, I will hold you"
Article 11 of Hague Convention V says:
"A neutral Power which receives on its territory troops belonging to the belligerent armies shall intern them, as far as possible, at a distance from the theatre of war."
To intern means to hold soldiers in a safe place so that they cannot return to the fighting.
- The neutral state may keep interned troops in camps.
- It decides whether officers may go free on their word of honour not to leave.
- Under Article 12, it must supply the food, clothing and relief that humanity requires. The cost is to be made good when peace comes.
- The Third Geneva Convention adds that such interned soldiers must receive, broadly, the treatment given to prisoners of war.
This explains Les Verrières. Switzerland did exactly this for the French army in 1871, long before the Hague Conventions were written. The soldiers were sheltered, but disarmed and held, so Swiss territory gave no military advantage to either France or its German enemies.
Exception: escaped prisoners of war (Article 13)
Prisoners of war who escape are not interned. Article 13 says:
"A neutral Power which receives escaped prisoners of war shall leave them at liberty. If it allows them to remain in its territory it may assign them a place of residence. The same rule applies to prisoners of war brought by troops taking refuge in the territory of a neutral Power."
Reason: an escaped prisoner was a captive, not a fighting force, and neutral territory must not become a second prison.
| Belligerent troops entering neutral territory | Escaped prisoners of war |
|---|---|
| Must be interned, as far as possible at a distance from the theatre of war (Article 11) | Must be left at liberty; may be assigned a place of residence if allowed to remain (Article 13) |
| They are a fighting force | They were captives; this rule also covers prisoners brought in by troops taking refuge |
Lawful acts of a neutral state: neutrality is not paralysis
Some acts may look like help to one side, yet the law treats them as lawful.
1. Defending neutrality (Article 10, Hague Convention V)
"The fact of a neutral Power resisting, even by force, attempts to violate its neutrality cannot be regarded as a hostile act."
If a belligerent army marches across the border, the neutral state may fire back without becoming a party to the war.
2. Humanity towards the wounded
Article 14 of Hague Convention V says:
"A neutral Power may authorize the passage over its territory of the sick and wounded belonging to the belligerent armies, on condition that the trains bringing them shall carry neither personnel nor war material. In such a case, the neutral Power is bound to take whatever measures of safety and control are necessary for the purpose."
Article 4 of the First Geneva Convention adds:
"Neutral Powers shall apply by analogy the provisions of the present Convention to the wounded and sick, and to members of the medical personnel and to chaplains of the armed forces of the Parties to the conflict, received or interned in their territory, as well as to dead persons found."
3. Relief for civilians (Article 70(2), Additional Protocol I)
"The Parties to the conflict and each High Contracting Party shall allow and facilitate rapid and unimpeded passage of all relief consignments, equipment and personnel provided in accordance with this Section, even if such assistance is destined for the civilian population of the adverse Party."
The words "each High Contracting Party" matter: they bind every state that has accepted the Protocol, including states that are not fighting at all.
4. Ordinary communication (Articles 8 and 9, Hague Convention V)
Under Article 8, a neutral state need not stop belligerents from using telegraph or telephone cables or wireless apparatus that belong to it or to private companies. Under Article 9, any restriction it chooses must apply equally to both sides.
| Forbidden | Permitted |
|---|---|
| A secret military station set up or used by a belligerent on neutral territory (Article 3) | Belligerent use of an ordinary public network open to all, such as cables or wireless apparatus of the neutral state or private companies (Article 8), with any restriction applied equally (Article 9) |
Neutral airspace
Neutral territory also has a sky. Its rules depend on the kind of aircraft.
Belligerent military aircraft
The strictest rule applies to military aircraft. Under customary law, reflected in the Hague Rules of Air Warfare drafted in 1923:
- belligerent military aircraft must not enter neutral airspace;
- the neutral state must use the means at its disposal to keep them out; and
- the neutral state must intern any such aircraft that lands, together with its crew.
Medical aircraft
Medical aircraft get a gentler regime. Article 37 of the First Geneva Convention says that "medical aircraft of Parties to the conflict may fly over the territory of neutral Powers, land on it in case of necessity, or use it as a port of call. They shall give the neutral Powers previous notice of their passage over the said territory and obey all summons to alight, on land or water."
For states that have accepted Additional Protocol I, Article 31(1) is stricter: "Except by prior agreement, medical aircraft shall not fly over or land in the territory of a neutral or other State not a Party to the conflict."
If a landed aircraft turns out to be a pretender, Article 31(3) is clear: "If the inspection discloses that the aircraft is not a medical aircraft, it shall be seized and the occupants treated in accordance with paragraph 4."
| Belligerent military aircraft | Medical aircraft (Article 37, First Geneva Convention) | Medical aircraft (Article 31, Additional Protocol I) |
|---|---|---|
| Must not enter neutral airspace; neutral must keep them out and intern any that land, with crew | May fly over, land in case of necessity, or use neutral territory as a port of call; must give previous notice and obey all summons to alight | Must not fly over or land except by prior agreement; an aircraft found on inspection not to be medical is seized |
Neutral waters and ports
At sea the rules are more detailed, because warships need ports. The provisions below are from Hague Convention XIII unless stated otherwise.
Passage is allowed (Article 10)
"The neutrality of a Power is not affected by the mere passage through its territorial waters of war-ships or prizes belonging to belligerents."
Passing through is allowed. Staying is what the law controls.
Staying is limited: the 24-hour rule (Article 12)
"In the absence of special provisions to the contrary in the legislation of a neutral Power, belligerent war-ships are not permitted to remain in the ports, roadsteads, or territorial waters of the said Power for more than twenty-four hours, except in the cases covered by the present Convention."
A roadstead is a sheltered anchorage near the shore.
Damage, repairs, armament and fuel (Articles 14, 17, 18 and 19)
- Longer stay for damage (Article 14): a warship may stay longer on account of damage or stress of weather, but it must leave once the cause is over.
- Repairs (Article 17): "In neutral ports and roadsteads belligerent war-ships may only carry out such repairs as are absolutely necessary to render them seaworthy, and may not add in any manner whatsoever to their fighting force." The local authorities of the neutral state decide which repairs are necessary.
- No added strength (Article 18): the port may not be used to add war material, armament or crew.
- Fuel (Article 19): "these vessels may only ship sufficient fuel to enable them to reach the nearest port in their own country."
Admiral Graf Spee (1939): In December 1939, after a battle with British cruisers, the German warship Admiral Graf Spee entered the port of Montevideo in neutral Uruguay. Its captain wanted a long stay. Uruguay, applying these rules, allowed 72 hours: enough to make the ship seaworthy, but not to rebuild its fighting power. Had the ship overstayed, Article 24 would have allowed Uruguay to make it incapable of going to sea for the rest of the war. On 17 December 1939, the captain took the ship just outside the harbour and scuttled it, that is, sank it deliberately.
Limits on numbers and departures (Articles 15 and 16)
Two further rules stop a neutral port from becoming a naval base or a battlefield.
Maximum number (Article 15): "In the absence of special provisions to the contrary in the legislation of a neutral Power, the maximum number of warships belonging to a belligerent which may be in one of the ports or roadsteads of that Power simultaneously shall be three."
Gap between departures (Article 16): "When war-ships belonging to both belligerents are present simultaneously in a neutral port or roadstead, a period of not less than twenty-four hours must elapse between the departure of the ship belonging to one belligerent and the departure of the ship belonging to the other. The order of departure is determined by the order of arrival, unless the ship which arrived first is so circumstanced that an extension of its stay is permissible."
Reason: without this gap, one warship could wait just outside the harbour and attack its enemy the moment it sailed.
Hospital ships (Article 32, Second Geneva Convention)
Hospital ships stand outside these limits. Article 32 of the Second Geneva Convention says that hospital ships and the other protected vessels it lists "are not classed as warships as regards their stay in a neutral port."
| Rule for belligerent warships | Provision |
|---|---|
| Mere passage through neutral territorial waters does not affect neutrality | Article 10, Hague Convention XIII |
| Stay in ports, roadsteads or territorial waters limited to 24 hours, unless the neutral's legislation provides otherwise | Article 12, Hague Convention XIII |
| Longer stay for damage or stress of weather, until the cause is over | Article 14, Hague Convention XIII |
| At most three warships of one belligerent in one port or roadstead at the same time, unless the neutral's legislation provides otherwise | Article 15, Hague Convention XIII |
| At least 24 hours between departures of enemy warships; order of departure follows order of arrival | Article 16, Hague Convention XIII |
| Only repairs absolutely necessary for seaworthiness; no addition to fighting force | Article 17, Hague Convention XIII |
| No adding war material, armament or crew | Article 18, Hague Convention XIII |
| Fuel only to reach the nearest port in their own country | Article 19, Hague Convention XIII |
| Overstaying ship may be made incapable of going to sea for the rest of the war | Article 24, Hague Convention XIII |
| Hospital ships are not classed as warships for their stay in a neutral port | Article 32, Second Geneva Convention |
Forms of neutrality
Instead of memorising a list, the forms of neutrality can be sorted by asking five questions.
1. How long does it last?
- Occasional neutrality: the usual case, adopted for one particular war.
- Permanent neutrality: the state is bound to stay out of every war. Switzerland is the classic example. Austria declared its permanent neutrality in 1955.
2. Where does it come from?
- Conventional neutrality: a treaty obliges the state to stay neutral.
- Voluntary neutrality: the state stays out by its own choice, and a voluntary choice can be reversed.
Sweden followed neutrality, later called military non-alignment, for about 200 years, yet freely joined NATO in 2024.
3. How much territory does it cover?
- General neutrality: the whole territory, which is the usual case.
- Partial neutrality: only a part of the territory. For example, the Aland Islands of Finland were neutralised and demilitarised by a convention of 1921.
4. How strict is it?
- Absolute or strict neutrality: no help to either side.
- Qualified neutrality: the state stays out of the fighting while giving some help to one side.
- Benevolent neutrality: an older label for a neutral with a friendly tilt towards one belligerent. It has largely fallen out of use.
Since the United Nations Charter outlawed aggression, some states and scholars argue that a state may help the victim of aggression without breaching neutrality. That view remains debated: treat it as a modern controversy, not a settled rule.
5. How is it defended?
Armed neutrality: a state keeps military strength ready to protect its neutral status, as Switzerland does with its citizen army.
| Question | Forms | Illustration |
|---|---|---|
| How long does it last? | Occasional / Permanent | Switzerland; Austria (1955) |
| Where does it come from? | Conventional (treaty) / Voluntary (own choice, reversible) | Sweden, which joined NATO in 2024 |
| How much territory does it cover? | General / Partial | Aland Islands of Finland (convention of 1921) |
| How strict is it? | Absolute or strict / Qualified (older label: benevolent) | Helping the victim of aggression remains debated |
| How is it defended? | Armed neutrality | Switzerland's citizen army |
Neutralisation
Neutralisation means fixing a state's neutrality for all future wars through an international agreement, so that other states recognise and respect it.
Switzerland's permanent neutrality was recognised by the great powers of Europe in 1815, at the close of the Napoleonic Wars.
A permanently neutral state carries duties even in peacetime. It must not join a military alliance or accept commitments that would pull it into a future war.
Permanent neutrality and United Nations membership
The question is whether a permanently neutral state can join the United Nations, whose members may be called upon to act against an aggressor.
- Swiss voters rejected UN membership in 1986.
- They approved it in a referendum on 3 March 2002.
- Switzerland became a member on 10 September 2002, and its neutrality survived.
The Charter's plan for members to place armed forces at the Security Council's disposal through special agreements under Article 43 has never been carried out, so no member can be compelled to send troops. Switzerland applies sanctions decided by the Security Council, yet still stays out of wars.
Permanent neutrality and UN membership can co-exist: because the Article 43 agreements were never made, no member can be compelled to send troops. Switzerland applies Security Council sanctions but stays out of wars.
The three problems answered
The fighter jet: it must not be refuelled and sent back to the war. It is a belligerent military aircraft on neutral territory, so the neutral state must intern the aircraft and its crew until the war ends.
The private drone factory: it does not, by itself, put the neutral state in breach, because Article 7 of Hague Convention V does not require a neutral state to stop private exports. But two limits apply: the government itself must never supply such weapons, and if it restricts exports at all, the restriction must apply equally to both sides.
The ambulance convoy: it may pass, but not with armed guards. Article 14 of Hague Convention V allows the passage of the sick and wounded only if the transport carries neither personnel nor war material. Remove the guards, and the convoy can cross.
Quick revision
- Neutrality is a bargain: the neutral state receives a shield and gives a promise in return.
- The shield protects its land, sea and sky.
- In return it makes four promises: "I will not arm you" (abstention); "I will not let you use my land" (prevention); "I will not favour either of you" (impartiality); "If you cross my border, I will hold you" (internment).
- Les Verrières, 1871: Switzerland sheltered the French army but disarmed and held it, so its territory gave no military advantage to either side. Every rule of neutrality falls into place around this example.
