An operation involving naval and air forces by which a belligerent completely prevents movement by sea from or to a port or coast belonging to or occupied by an enemy belligerent. To be mandatory, that is, for third States to be obliged to respect it, the blockade must be effective. This means that it must be maintained by a force sufficient to prevent all access to the enemy coast. The belligerent must declare the existence of the blockade. The belligerent must also specify and the starting date, geographical limits of the blockaded territory and time allowed to neutral vessels to leave. This declaration must be notified to all neutral Powers and to the local authorities.
Suggested readings :
MEYROWITZ Henri, “Le Protocole additionnel I aux Conventions de Genève de 1949 et le droit de la guerre maritime”, in RGDIP, Vol. 89/2, 1985, pp. 243-298.
SWAYZE Frank B., “Traditional Principles of Blockade in Modern Practice: United States Mining of Internal and Territorial Waters of North Vietnam”, in JAG Journal, Vol. 29/2, 1977, pp. 143-173.
WHITEMAN Marjorie M., “Blockade”, in Digest of International Law, Vol. 10, Chapter XXXI: Belligerent Interference with Neutral Commerce, US Department of State Publication 8367, Washington DC, Government Print. Off., 1968, pp. 861-879.
Further reading :
ROWSON S.W.D., “Modern Blockade: Some Legal Aspects”, in BYIL, Vol. 23, 1946, pp. 346-353.