Naval Blockade Under International Law
A naval blockade is a military operation to prevent passage of vessels to or from an enemy's coastline or ports. Under the laws of naval warfare codified in the San Remo Manual (1994) on International Law Applicable to Armed Conflicts at Sea, a blockade is legally permissible during armed conflict, but must be declared formally, must not bar access to neutral ports, must be effective, and must not cause disproportionate harm to civilian populations.
- The San Remo Manual (1994) is the key contemporary reference on the law of naval warfare; it codifies conditions for a lawful blockade.
- A blockade that cuts off humanitarian supplies can be challenged as a violation of international humanitarian law.
- The US is not a party to UNCLOS (United Nations Convention on the Law of the Sea, 1982), but recognises most of its provisions as customary international law.
- UNCLOS Article 37–44 govern "transit passage" through international straits — a right that cannot be suspended even during armed conflict.
● Tracked since April 12, 2026 · last seen July 14, 2026 · updates as the daily brief publishes
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