■ Blockade

A blockade is a military operation employed by belligerents to control, prevents or blocks partially or completely the flow of goods, persons to and from specific areas, be they territories, regions under their control or of the enemy. It can include all maritime movement to or from a port or coast (naval blockade) but blockades may also be conducted through the air (aerial blockade). A military operation that surrounds, isolates or encircles an area on land is known as a siege . It is also important to distinguish between the terms blockade and embargo . An embargo is not an act of war but a type of multilateral or unilateral economic sanction that may be adopted under the aegis of the United Nations (UN), a regional organisation or a State, to try to change the behaviour of a State or to force it to comply with a decision, an international order.

➔ Embargo ▸ Siege

A blockade is an act of war that is regulated by international law—namely, by the Declaration Respecting Maritime Law adopted in Paris on 16 April 1856 and by articles 1-21 of the Declaration Concerning the Laws of Naval War adopted on 26 February 1909 in London. The San Remo Manual on International Law Applicable to Armed Conflicts at Sea (SRM) adopted on 12 June 1994 also provides some legal interpretation in paragraphs 67(a), 93-104, 146(f) and 153(f). In order for it to be binding to third party States, it must be effective, and its existence must be officially declared along with a starting date, the territorial geographical limits and a time provided for neutral vessels or aircrafts to be able to leave the area (SRM, arts. 93 and 94).

As a method of warfare, a blockade must comply with international humanitarian law (IHL) and customary IHL (CIHL), which are applicable in both situation of international and non-international armed conflict. This means respecting the principles of military necessity, distinction and proportionality, while protecting civilians and civilian objects. (API, arts. 48, 51(2), 51(5)(b), 52(2) and 57(2)(a)(iii); APII; art. 13(2); CIHL rules 1, 7, 11, 14, 15, 17 and 22).

It is clear that under IHL and CIHL, States are obliged to allow the free passage of relief of an exclusively humanitarian and impartial nature that is indispensable to the survival of the civilian population (GCIV, arts. 23 and 59; API, arts. 70-71; APII, art. 18(2) and CIHL rules 53-56). This is regardless of whether the situation is a blockade, siege or an embargo. IHL foresees no exception to this duty based on the argument of imperative military necessity.

A blockade will be deemed unlawful under IHL if it is implemented in a way that denies the civilian population access to essential goods necessary for their survival. Furthermore, any blockade, siege or embargo that is implemented with the purpose of causing starvation of the civilian population is prohibited. (SRM, art. 102; GCIV, arts. 23 and 55, API, art. 54, APII, art. 14 and CIHL rules 53, 55 and 56). Starvation of civilians is a war crime under the International Criminal Court’s (ICC) jurisdiction in the context of an international armed conflict (arts. 8(2)(b)(xxv) of the Rome Statute). Starvation of civilians and obstruction of humanitarian relief are not war crimes under the general article 8 (2)(e) of the Rome Statute applicable to non-international armed conflict. However, in 2019, the Assembly of States Parties to the Rome Statute adopted an amendment to the definition of war crimes applicable in NIAC detailed in article 8(2)(e). The new article (8)(2)(e)(xix) prohibits as a war crime in NIAC, the intentional use of starvation of civilians as a method of warfare by depriving them of objects indispensable to their survival, including the willful impeding of relief supplies. This amendment is only applicable to the 16 States that have accepted it as of August 2024.

However, such practices can still be prosecuted as crimes against humanity if they meet the conditions of the Rome Statute definition, which includes the intentional infliction of conditions of life, inter alia the deprivation of access to food and medicine, calculated to bring about the destruction of part of a population (art. 7(2)(b) of the Rome Statute).

The blockade of a State’s ports or coastlines by the armed forces of another State’s could also constitute an act of aggression that could lead to prosecution by the ICC under the specific jurisdictional requirements for the crime of aggression set out in the Rome statute of the ICC (art. 8 bis (2)(c) of the Rome Statute).

There have been many instances in the past where blockades and sieges have limited or deprived access to essential supplies for civilian populations. The chapter on siege presents the jurisprudence of international tribunals regarding the provision of humanitarian assistance in such situations. Overall, only a small number of decisions of international tribunals elaborate on the concept of blockade. On 31 May 2010, Israeli soldiers raided a flotilla of six ships carrying humanitarian aid and attempting to break Israel’s blockade of the Gaza Strip. Despite the fact that the Israeli military operation resulted in the death of 9 persons, the ICC Prosecutor decided not to investigate the case (decision of the Prosecutor on 16 November 2014, confirmed by final decision of the Prosecutor on 29 November 2017). However, the involvement of the ICJ and ICC in the investigation of war crimes and crimes against humanity committed during the war between Israel and Hamas in the Gaza Strip may lead to relevant decisions on blockade in the coming years.

➔ Aggression ▸ Embargo ▸ Famine ▸ International Court of Justice ▸ International Criminal Court; ▸ Methods (and means) of warfare ▸ Protected objects and property ▸ Relief ▸ Right of Access ▸ Sanctions Committees ▸ Sanctions (diplomatic, economic, or military) ▸ Siege ▸ War ▸ War crimes/Crimes against Humanity