Naval Blockade

• Author: Magne Frostad
• Pages: 45-75

Arctic Review on Law and Politics

Vol. 9, 2018, pp. 195–225

195

Peer-reviewed article

© 2018 Magne Frostad. This is an Open Access article distributed under the terms of the Creative Commons Attribution-

NonCommercial 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), allowing third parties to share

their work (copy, distribute, transmit) and to adapt it, under the condition that the authors are given credit, that the work

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Citation: Magne Frostad. “Naval Blockade’’ Arctic Review on Law and Politics, Vol. 9, 2018, pp. 195–225.

http://dx.doi.org/10.23865/arctic.v9.1123

*Correspondence to: Magne Frostad. magne.frostad@uit.no.

Naval Blockade

Magne Frostad

Faculty of Law, UiT The Arctic University of Norway

Abstract

Naval blockade is an old form of warfare where the current restatement of customary international

law on this issue – the 1994 San Remo Manual – leaves something to be desired. The article con-

siders the history of the concept and its current regulation like the requirements for establishing a

naval blockade and addresses also issues in relation to its enforcement.

Keywords: Blockade; Mavi Marmara;Yemen; San Remo Manual

Responsible Editor: Øyvind Ravna, UiT - The Arctic University of Norway, Tromsø,

Norway.

Received: December 2017; Accepted: May 2018; Published: August 2018

1. Introduction of the concept

A blockade might be dened legally as “an operation by a belligerent State to prevent

vessels and/or aircraft of all States, enemy as well as neutral, from entering or exiting

specied ports, airelds, or coastal areas belonging to, occupied by, or under the

control of an enemy belligerent State”.1

The purpose of a naval blockade is to help achieve the overall objective of the

use of armed force – to get the enemy to agree to terms favorable to you – through

undermining the enemy’s war effort by interdicting in- and outgoing maritime traf-

c. Moreover, although blockades in earlier times were largely aimed at the economy

of the enemy, today they are often an integral part of militar y operations directed

against the enemy’s military assets.2 A blockade also “avoids the need to distinguish

between the cargoes carried by neutral ships, and so overrides the law of contra-

band”,3 and it is the only measure of traditional naval warfare which makes it possi-

ble to interfere with enemy exports.4

The rules of naval warfare have always been a compromise between the interests

of larger naval powers, as well as between these powers and states likely to remain

Magne Frostad

196

neutral during a naval encounter. As such, blockade law reects naval tactics and

strategies and is largely a product of customary international law developed over

time “[t]hrough silence and acquiescence”.5

Naval blockades must be differentiated from situations where a coastal state uses

its powers under the law of the sea to enforce restrictions on the use of its territorial

sea, in that zone itself and in its contiguous zone.6 An example of this would be using

the authority granted by the United Nations Convention on the Law of the Sea

(UNCLOS) Art. 25 (3) to suspend innocent passage through a state’s territorial sea

during ongoing hostilities. Thus, Sri Lankan restrictions, enforced in its territorial

sea, on shipments to the Tamil Tigers were inherently different from a blockade.7

Likewise, the government of Yemen could decide to prohibit the use of rebel held

ports and suspend innocent passage through its territorial sea.8 By authorizing Saudi

forces, the latter would be able to undertake enforcement in Yemeni maritime zones

to the same extent that Yemen is itself entitled to do so.9

Moreover, a ag state interfering with a vessel ying its ag, even if it is a rebel

vessel, is not a blockade.10 Occasionally, the term blockade is wrongly used in con-

nection with embargos, which at least partially differ from blockades, e.g. because

they include landside restrictions on what may pass a border.11 Thus, criticism of the

Israeli blockade of the Gaza Strip largely centers on landside restrictions enacted by

Israel, rather than the consequences of the seaside blockade.12

A related concept is the nineteenth century custom of pacic blockade.13 A pacic

blockade was used as a tool of reprisal in relation to breaches of international law

undertaken by the party against whom the pacic blockade was established. The

essential difference between this type of “blockade” and the regular one was the

absence of an intention to establish a state of war between the involved states.14 One

issue raised by this practice is whether a pacic blockade could be enforced against

vessels of non-participating states.15 Another more fundamental issue is whether the

use of force may ever be used for the purpose of reprisal.16 Hindering access to or

from a foreign coast presumably constitutes a use of force, either through aggressive

obstruction of the navigation of vessels, or through the use of boarding or similar to

achieve compliance. The “quarantine” of Cuba in 1962 would seem to have a ques-

tionable legal foundation,17 especially as none of the well accepted exceptions to the

prohibition on the use of force seems applicable.

2. Historical development

Historically, blockades resembled maritime sieges.18 An early example of a maritime

siege is the Athenian blockade in 425 B.C. of the island Sphacteria, which forced a

Spartan garrison to surrender.19 A blockade was “considered an extension of invest-

ment of a fortress on land, and it was therefore not legally available in relation to

unfortied ports, let alone a whole coastline.”20 The Dutch blockade of the Spanish

Netherlands in 1584,21 and Grotius’ support for this, “translated the requirement