Israel’s Gaza Blockade Is Unequivocally Consistent with the San Remo Manual

The San Remo Manual on International Law Applicable to Armed Conflicts at Sea, which occupies a curious position in modern international law, is one of the most frequently cited maritime law documents in contemporary military and diplomatic debates, yet it is not a treaty, a convention, or binding statute. Rather, it is a restatement and synthesis: an attempt by distinguished experts in naval warfare, humanitarian law, and the law of armed conflict to gather existing customary law, treaty obligations, state practice, and legal doctrine into a coherent framework suitable for modern naval warfare. Few documents have exercised such influence without possessing formal legislative force, and fewer still have become so central to one of the defining legal controversies of the 21^st century: Israel’s naval blockade of Gaza.

The Manual emerged from the changing realities of naval conflict after World War II. The classic laws governing naval warfare had largely been shaped by 19^th-century practice and by the Hague Conventions of 1899 and 1907, but warfare evolved dramatically during the 20^th century: submarines, aircraft carriers, missile systems, asymmetric warfare, terrorism, and the increasing entanglement of civilians in modern conflicts had all complicated the traditional legal categories so that the law had become fragmented. Some rules were treaty-based, some customary, and some heavily disputed, and during the Cold War, major naval powers often preferred ambiguity to codification. By the late 1980s, however, there was growing concern among scholars and military lawyers that the absence of a modern and reasonably authoritative statement of the law governing armed conflict at sea risked confusion, escalation, and abuse.

The result was a series of expert meetings convened under the auspices of the International Institute of Humanitarian Law in San Remo, Italy, with the principal work taking place between 1988 and 1994. The participants included distinguished naval officers, jurists, government legal advisers, and academics from numerous countries and legal traditions. Among the most influential figures were Louise Doswald-Beck, who served as editor of the accompanying explanatory commentary, and several prominent military law specialists from the United States, the United Kingdom, Canada, Germany, Israel, and other states with serious maritime interests. The process was deliberately international and professionally diverse, as the drafters sought not to create new law but to articulate what they believed existing international law already was, or was evolving toward.

The resulting document, formally adopted in 1994, quickly became known simply as the San Remo Manual. Its authority derived not from ratification but from expertise, and militaries, naval academies, ministries of defense, and legal scholars began treating it as an important interpretive guide. Western navies in particular found it valuable because it translated scattered precedent and doctrine into practical operational rules, and it became heavily cited in military manuals, legal memoranda, academic articles, and discussions at the United Nations.

Support for the Manual came especially from states and scholars who favored a rule-based system governing armed conflict while also recognizing the continuing reality of naval warfare. The United States, while not formally adopting the Manual as binding law, treated many of its provisions as reflecting customary international law. NATO countries generally viewed it favorably, and Israel also regarded it as a serious and highly relevant articulation of maritime law, particularly because the Manual addressed blockades, contraband, neutral shipping, humanitarian access, and asymmetric warfare.

Criticism came from several directions. Some humanitarian activists argued that the Manual too readily accepted traditional military prerogatives and insufficiently constrained the use of force at sea, while others objected that it gave excessive latitude to belligerents conducting blockades. Certain scholars from the Global South argued that the document reflected the strategic assumptions of powerful naval states and inadequately protected weaker states and civilian populations. Still others criticized its status as “soft law,” contending that a nonbinding expert document should not acquire quasi-authoritative influence absent formal state consent.

Nonetheless, even many critics conceded that the Manual possessed substantial descriptive value. Courts, governments, and scholars repeatedly relied upon it because there existed no comparably comprehensive modern statement of naval wartime law. Thus, the Manual’s practical importance became enormous despite its technically nonbinding status.

It is equally important to understand what the Manual was intended to accomplish and what it was not intended to accomplish. It was not designed as a moral manifesto abolishing war at sea, nor was it intended to prevent states from using naval blockades. Quite to the contrary: The Manual explicitly recognizes blockade as a lawful instrument of armed conflict, provided certain conditions are met. The drafters accepted the long-established principle that belligerents may seek to weaken an enemy’s military capabilities through maritime restrictions and, as such, the Manual focuses not on eliminating blockade, but on regulating it.

Its enforcement mechanisms are indirect rather than centralized. The Manual created no international police force, tribunal, or sanctions regime; compliance depends largely on existing international-law structures – domestic military discipline, diplomatic pressure, international tribunals where jurisdiction exists, state practice, and political legitimacy. A state violating the laws of naval warfare may face international condemnation, litigation, sanctions, or reciprocal measures by other states, but the Manual itself contains no independent machinery for punishment.

These realities become critically important in evaluating Israel’s naval blockade of Gaza. Since Hamas seized effective control of Gaza in 2007 after violent clashes with Fatah, Israel has faced a territory governed by an organization openly committed, as set forth in its foundational charter and repeated public declarations, to Israel’s destruction. Hamas is not merely a political movement – it is an armed organization responsible for suicide bombings, rocket attacks, kidnappings, and mass-casualty assaults against Israeli civilians. Numerous states, including the United States, the United Kingdom, Canada, and the European Union, designate Hamas in whole or in substantial part as a terrorist organization.

The strategic reality confronting Israel is therefore far from theoretical. Hamas has repeatedly sought to import weapons, explosives, missile technology, dual-use materials, and military equipment into Gaza; smuggling routes have included tunnels from Egypt, overland trafficking, and maritime channels; Iran and other actors hostile to Israel have repeatedly attempted to transfer weapons to Hamas and affiliated groups; and Israeli interceptions over the years have included ships allegedly carrying rockets, mortars, explosives, and advanced military systems destined for Gaza-based militants.

Under the San Remo Manual, a blockade is lawful if several core conditions are satisfied: The blockade must be declared and notified; it must be effective; it must not bar access to neutral ports and coastlines; it must not have the sole purpose of starving civilians or denying them objects essential for survival; and the damage to the civilian population must not be excessive in relation to the concrete and direct military advantage anticipated.

Israel’s blockade, properly understood, falls squarely within these principles.

First, Israel formally declared the blockade and publicly communicated its existence and operational parameters. This is not a secret or arbitrary maritime closure; the blockade has been repeatedly announced through official naval channels and diplomatic communications, and merchant vessels and humanitarian organizations are fully aware of its existence.

Second, the blockade has been effective in the classic legal sense because Israel has maintained actual naval enforcement capability in the relevant maritime zone. A blockade that exists only on paper is unlawful under traditional law because it deceives neutral shipping without genuine enforcement, but Israel’s blockade plainly does not suffer from that defect.

Third, Israel’s purpose is military and security-oriented, not genocidal or starvation-based – a point that is essential and frequently distorted in political rhetoric. As discussed above, the San Remo Manual does not prohibit hardship resulting from blockade – historically, blockade almost inevitably imposes hardship – but rather blockade whose purpose is starvation of civilians as such, or whose collateral civilian damage becomes disproportionate.

Israel has consistently maintained that the blockade exists to prevent the importation of weapons and military materiel into Hamas-controlled territory, a claim that is strongly supported by the historical evidence. Hamas and allied groups have used imported materials to construct rockets, tunnels, military infrastructure, explosives, and fortified positions. The October 7, 2023 attacks dramatically reinforced Israeli perceptions that Hamas is not merely a nuisance actor but a heavily armed and operationally sophisticated enemy willing to carry out mass atrocities against civilians.

Critics often argue that Gaza’s civilian suffering automatically renders the blockade unlawful. Under the San Remo framework, however, that conclusion is entirely disingenuous. The relevant legal question is not whether hardship exists – a blockade by definition exerts significant pressure – but whether the blockade’s military objectives are legitimate and whether humanitarian obligations are being addressed within the constraints of armed conflict.

The San Remo Manual itself expressly contemplates the passage of humanitarian assistance under certain circumstances, and Israel has repeatedly permitted substantial quantities of food, medicine, fuel, and humanitarian supplies into Gaza through monitored channels. Even most critics generally acknowledge that Israel has not attempted to hermetically seal Gaza from all goods whatsoever, and the existence of inspections, controlled crossings, coordinated aid deliveries, and internationally supervised humanitarian mechanisms strongly undermines the claim that the blockade’s sole or primary purpose is civilian starvation.

Another common criticism alleges that because Gaza is so densely populated, any blockade necessarily violates proportionality, an argument that also stretches the law beyond recognition. International humanitarian law does not impose a rule that military measures become unlawful simply because the opposing force embeds itself among civilians; indeed, Hamas has frequently been accused by Israel, the United States, and various rational observers of deliberately operating within civilian infrastructure, including residential neighborhoods, schools, mosques, and hospitals. If the mere presence of civilians automatically invalidated a blockade, non-state armed groups would possess a legal incentive to maximize civilian entanglement – and civilian deaths, which remains one of the most important goals of Hamas and its supporters.

The proportionality analysis required by the San Remo Manual, which is more nuanced, requires the weighing of anticipated military advantage against expected civilian harm. Israel’s stated military advantage is the prevention of weapons importation into a territory controlled by an armed organization dedicated to violent conflict with Israel and, given Hamas’s extensive history of rocket warfare, tunnel construction, hostage-taking, and cross-border attacks, Israel possesses exceptionally strong grounds for treating maritime interdiction as a military necessity.

The 2011 report of the United Nations Secretary-General’s Panel of Inquiry on the 2010 Gaza flotilla incident, commonly called the Palmer Report, is especially significant in this regard. Although controversial and criticized by some activists, the Panel concluded that Israel faced a genuine security threat from Gaza and that the naval blockade was “a legitimate security measure” consistent with international law. The Panel further concluded that the blockade’s implementation complied in principle with the requirements of international law, though it criticized aspects of the force used during the interception of the Mavi Marmara.

This distinction is legally crucial. One may debate whether particular enforcement operations were tactically wise or proportionate without invalidating the blockade itself and, under the law of armed conflict, an otherwise lawful military measure does not become inherently unlawful merely because individual enforcement actions may be questioned.

Opponents of the blockade frequently invoke the manifestly false and deceptive propaganda alleging “collective punishment,” a phrase that carries immense emotional and moral force, particularly because collective punishment is prohibited under the Fourth Geneva Convention. However, actual legal analysis requires precision rather than mere slogans. Collective punishment refers to penalties imposed on civilians for offenses they did not personally commit, while a blockade aimed at preventing arms smuggling to an enemy entity is not automatically transformed into collective punishment simply because civilians experience economic or humanitarian consequences.

Historically, virtually all major naval blockades have affected civilian populations. The Allied blockade of Germany during the First World War had devastating civilian consequences, as did blockades during the Napoleonic era, the American Civil War, and numerous later conflicts. The San Remo Manual was drafted with full awareness of this historical reality, and its drafters nevertheless preserved blockade as a lawful military instrument because states continue to regard it as militarily necessary under some circumstances.

Another argument advanced by critics is that Israel, because of the degree of control it exercises around Gaza, remains an occupying power and therefore may not blockade territory it occupies – a dubious claim at best. Israel withdrew its settlements and permanent military presence from Gaza in 2005 and Hamas subsequently seized internal control. But even assuming, strictly arguendo, that aspects of occupation law continue to apply, that would not automatically invalidate a naval blockade directed at preventing organized armed attacks because international law does not require a state to allow unrestricted maritime importation of weapons into territory from which hostile operations are launched against its civilian population.

Thus, in sum, opposition to Israel’s blockade almost invariably depends less on the actual text of the Manual than on broader political objections to Israeli policy generally. Legally, Israel’s case pursuant to the criteria of the Manual is formidable.

The broader significance of the debate extends beyond Israel alone. If states facing persistent armed attacks from coastal territories governed by hostile armed organizations are denied the ability to interdict maritime weapons flows, the practical utility of naval blockade in modern international law would largely disappear. That would present not merely a reinterpretation of the San Remo Manual but a fundamental transformation of the law of naval warfare itself. (That the United States more than satisfies the conditions of the Manual in its naval blockade of Iran is another topic for another day.)