Can Neutral Ships Be Lawfully Attacked? Decoding Maritime Conflict Rules

A concise analysis of the Law of Naval Warfare, UNCLOS transit rights, the San Remo Manual exceptions, and India's options following merchant seafarer casualties.

Published: June 30, 2026 Read Time: 8 mins Author: GyanGram Editorial

Merchant tanker ship under missile fire with scales of justice overlay — Visual representation of the legal and physical threats to neutral merchant shipping in active combat zones.

Under international law, neutral merchant vessels enjoy broad protection against attacks during armed conflict, codified in international humanitarian law (IHL) and the 1994 San Remo Manual. A neutral ship loses this protection only if it carries contraband, breaches a declared blockade, or actively contributes to the enemy's military actions. Attacks justified by blockades must also satisfy the UN Charter (Article 2(4) and Article 51), which renders the blockade itself unlawful if it lacks UNSC authorization or valid self-defense claims.

Syllabus Connection: GS Paper II & III

GS Paper 2: Important International institutions, agencies and fora (UNCLOS, UN Charter), and bilateral, regional, and global groupings affecting India's interests.
GS Paper 3: Security challenges and their management in border/maritime areas.

1. Conflict Rules

Naval Warfare vs. Law of the Sea

Naval operations are governed by two distinct frameworks under international law: the **Law of Naval Warfare** (conduct of hostilities at sea) and the **Law of the Sea** (maritime boundaries and navigation rights).

UNCLOS (Law of the Sea): Establishes maritime zones (Territorial Sea, Contiguous Zone, EEZ, High Seas) and guarantees the right of transit passage through international straits like the Strait of Hormuz (Articles 37–44).
Law of Maritime Neutrality: A branch of International Humanitarian Law (IHL) that prevents belligerents from expanding hostilities to neutral territory and protects neutral commerce from arbitrary capture.

"The UN Charter regulates the legality of starting a conflict (jus ad bellum), while IHL regulates the conduct of that conflict (jus in bello) through core principles of distinction, proportionality, and precaution."
— San Remo Manual Restatement

2. Losing Protection

When Do Neutral Ships Lose Protected Status?

Neutral merchant vessels and their seafarers are civilian objects and are generally protected from attack. However, under **Paragraph 67 of the 1994 San Remo Manual**, they can lose this protection under three specific conditions:

Infographic illustrating the three conditions under which neutral ships lose protection under the San Remo Manual — Figure 1: Pathways to loss of protected status for neutral merchant vessels under international maritime law.

Even if these conditions are met, a belligerent cannot immediately attack. They must first issue a **prior warning**, demand a halt, and attempt to visit and search the vessel. Active force is only permitted if the vessel refuses compliance or actively resists search.

3. The Oil Tanker Dispute

The Oil Tanker Dispute: "Military Objective" vs. "War-Sustaining"

The U.S. strikes against tankers like the *Settebello* highlight a critical legal dispute over what constitutes a "military objective" at sea:

Legal Doctrine	Core Premise	Oil Tanker Status
Traditional IHL Rule	Objects must make an effective, direct contribution to military actions to lose civilian status.	Protected. Ordinary commercial exports are too remote from military operations, even if they generate government revenue.
U.S. "War-Sustaining" Theory	Objects that finance or sustain the enemy's war effort (e.g., oil exports) are legitimate military targets.	Legitimate Target. Treating commercial cargo as contraband if it funds the state's military budgets.

Additionally, while blockades are recognized under the San Remo Manual, their implementation must comply with the UN Charter. A blockade established without UN Security Council authorization or a valid self-defense claim under Article 51 is an illegal use of force (*jus ad bellum* violation), making any resulting attack on neutral vessels unlawful.

4. Options for India

India's Legal Options Under International Law

The deaths of three Indian seafarers aboard the *Settebello* allow India to pursue legal claims against the attacking state under three distinct doctrines:

State Responsibility: Invoking responsibility for an internationally wrongful act (an unlawful blockade and attack on neutral shipping).
Diplomatic Protection: Bringing an inter-state legal claim to seek compensation and accountability on behalf of the deceased nationals.
Independent Investigation: Demanding impartial multilateral probes to establish facts and prevent arbitrary attacks in international straits.

Frequently Asked Questions

What protections do neutral merchant ships have under international law?

Neutral merchant vessels are generally protected from attack during armed conflicts under International Humanitarian Law (IHL) and the law of naval neutrality. Belligerents are prohibited from targeting, capturing, or interfering with neutral vessels engaged in ordinary commercial activities, including carrying non-contraband cargo like food, fertilizer, or oil, outside of declared blockade zones.

Under what conditions does a neutral vessel lose its protected status?

According to Paragraph 67 of the San Remo Manual (1994), a neutral merchant vessel loses its protection and may be targeted only if: (1) It carries contraband or breaches a declared blockade, and after prior warning refuses to stop or submit to visit and search; or (2) It makes an effective contribution to the enemy's military action (e.g., carrying troops, transmitting tactical intelligence, or sailing as an auxiliary).

What is the difference between Jus ad Bellum and Jus in Bello in naval blockades?

Jus ad Bellum refers to the legality of going to war or establishing a blockade under the UN Charter (requiring UNSC authorization or Article 51 self-defense). Jus in Bello refers to the legal conduct within that blockade under naval warfare rules (impartial application, declaration, effectiveness). Even if a blockade complies with Jus in Bello rules, it remains unlawful under Jus ad Bellum if it constitutes an unauthorized use of force.

What is the U.S. 'war-sustaining' target theory?

The 'war-sustaining' theory is a contested legal doctrine used by the U.S. which argues that commercial objects (like oil exports) that generate revenue to finance an enemy's war effort can be treated as legitimate military objectives. Traditional international law rejects this, asserting that commercial exports are too remote from military operations to be targeted unless they directly contribute to military actions.

What legal remedies does India have for seafarer casualties on neutral ships?

India has three primary legal pathways under international law: (1) Diplomatic Protection to bring inter-state claims on behalf of injured nationals; (2) Invoking State Responsibility for internationally wrongful acts committed by belligerents; and (3) Demanding independent investigations, explanations, and financial compensation from the attacking state.

GyanGram Editorial Note

This article is based on the essay "Can neutral ships be lawfully attacked?" by Kartikey Singh. Formatted for UPSC GS Paper II (International Relations) and GS Paper III (Maritime Security) preparation.