Attack on the MV Conscience: Issues Related to Blockade Law

The MV Conscience is reportedly a Palau-flagged “passenger vessel” currently operated for a nongovernmental organization (NGO) called the “Freedom Flotilla Coalition.” The coalition, also called the Gaza Freedom Flotilla, is an international activist group formed in 2010 to “break Israel’s more than 17-year illegal and inhumane blockade of the Gaza Strip.”

On May 2, 2025, as the Conscience was underway in the High Seas outside the Maltese Territorial Sea, two drones attacked the vessel’s bow, damaging it. According to one news report, “[t]his led to a loss of power on the vessel and caused damage to the front of the ship.”

Reportedly delisted from Palau’s vessel register the day before the attack, the Conscience departed the Tunisian port of Bizerte on April 29, 2025. It was taking part in what the NGO described as a “nonviolent action” carried out “under a media black out to avoid any potential sabotage” in which “[v]olunteers from over 21 countries travelled to Malta to board the mission to Gaza, including prominent figures” such as climate activist, Greta Thunberg. There is also no doubt—as the NGO specifically confirmed—that the intended destination for the cargo on board the Conscience was the Gaza Strip, and that the vessel intended to breach the Israeli naval blockade.

The NGO blamed Israel for the attack, pointing to “flight-tracking data showing an Israeli C130 Hercules aircraft fl[ying] in the direction of Malta in the hours before the attack.” Although no crew members or passengers aboard the Conscience suffered injuries, reports as to the number of people on board the vessel at the time of the incident vary. The NGO, for example, claimed there were 30 people on board. Maltese authorities, on the other hand, reported there were sixteen people on board (twelve crew members, four passengers).

As to material damage, despite suffering a small fire and initial fears the Conscience would sink, the vessel is reportedly in a readily repairable state. “The Malta government said a surveyor had inspected the vessel and found it needed minor repairs in order to sail to its next destination,” read one news report. “The ship’s hull and engine room were found in good or satisfactory condition and free from water ingress. Most of the important equipment on the vessel, such as the two main engines, the two generators, the bow thrust, and the fire extinguishers, were operational.”

Although Maltese authorities were initially hesitant to allow the vessel to enter Malta even prior to the attack, they have since agreed to facilitate repairs to the vessel “in international waters.” According to the Times of Malta, “the ship is uninsured and unclassified” and “does not carry statutory certification.” The report continued, “It is unclear whether this is a direct consequence of the ship’s delisting. While the loss of a ship’s flag does not automatically cancel its insurance or class, it typically leads insurers and classification societies to withdraw their certification.” As of the date of this post, the Conscience is still in the vicinity of Malta, at anchor just outside the Maltese Territorial Sea.

In this post, I will briefly set out the background to the Gaza naval blockade, with the caveat that opinions as to the lawfulness or validity of this blockade vary. However, for the purpose of the analysis concerning blockade law, I will assume there is a valid naval blockade in place. I will then note three issues that could be relevant to assessing the incident from the perspective of blockade law: (1) the location of the incident in that it is quite distant from the blockaded area; (2) the nature of the cargo (claimed to be humanitarian aid); and (3) the (un)lawfulness under blockade law of the attack itself.

Background: The Israeli Blockade of Gaza

Naval blockade is “a belligerent operation intended to prevent vessel traffic from all States from entering or leaving specified coastal areas that are under the sovereignty, occupation, or control of an enemy. Such areas may include ports and harbors, the entire coastline, or parts of it” (Newport Manual, para. 7.4.1. For more detail as to the requirements for a valid blockade, see von Heinegg; Drew; San Remo Manual (arts. 93–104);Newport Manual, and previous posts by Fink; Pedrozo; Lott; Guilfoyle; and others).

The current blockade in relation to the Gaza Strip has its origins in the general blockade Israel declared in 2007 and implemented more specifically in a naval context in 2009 (see Turkel Commission Report Part I, paras. 48–50; Benvenisti, p. 977). After the events of October 7, 2023, Israel tightened the land, air, and sea blockade in both rigour and scope, and in March 2025, made the blockade even more comprehensive (i.e., allowing no exceptions). The International Court of Justice (ICJ) and the International Criminal Court (ICC) are now considering the post-October 7 blockade’s impact on civilians in the Gaza Strip.

In relation to the 2010 Mavi Marmara incident (which also took place in the context of the naval blockade off the Gaza Strip), the ICC report issued by the Office of the Prosecutor accepted the potential validity of the naval blockade (paras. 18, 32, n. 42). Nevertheless, views on the lawfulness or validity of the naval blockade vary. One key issue is whether the conflict in Gaza is an international armed conflict (IAC) or a non-international armed conflict, which has implications for the availability de jure of blockade (which, in turn, is only available in situations of IAC or recognised belligerency).

But for the purposes of this analysis, I will assume there is a lawful blockade while also noting the scope and stated purpose of the broader blockade since the 2025 shift in policy. That is, these recent specific statements as to the intended consequences for the civilian population have perhaps brought the blockade’s lawfulness in terms of implementation, but not existence, into question.

Issue 1: Where the Incident Occurred

The incident occurred just outside the Maltese Territorial Sea, more than 1,000 nautical miles (nm) from Israel. The naval blockade “line” off the coast of Gaza is about 60 nm from the Gaza coast. The question, therefore, is: Can a blockade interdiction take place beyond a specifically declared blockaded zone, so long as it stays out of neutral or third-State territorial seas?

The short answer is yes. Indeed, if there is a reasonable belief that a vessel intends to breach the blockade, then it can be interdicted even at a great distance. One might describe this as an “attempt” to breach a blockade. The Newport Manual describes situations of “attempt” to include where “a vessel sails towards the blockaded area with the intention of breaching the blockade” (para. 7.4.7(3)). That is, while the vessel did not actually breach the blockade (as Israel intercepted the vessel before it reached the blockade “line”), the Conscience was liable to interdiction and disruption due to its clearly stated intent.

In this particular case, however, there is a complication in the form of an intended intervening port visit. The intended call into Malta may or may not have affected the intended voyage, as the Maltese authorities may have prevented the vessel from departing port, given the vessel’s recent statelessness. Put differently, Israel’s need to enforce its blockade prior to the Conscience’s actual crossing of the blockade line would have been clearer had Israel waited until the vessel departed from its final port of call, as the port State may have taken action to prevent the continuation of the voyage altogether. Alternatively, the Conscience may have subsequently altered its plans for another reason, such as flag State, political, commercial, or insurance pressures.

However, a definitive view on the validity of the location and the effects of an intervening intended port call is ultimately not the critical concern in this case. This is because it is the conclusion to be drawn in relation to issue 3 (the attack) that is actually the threshold matter.

Issue 2: The Claimed Nature of the Cargo as Humanitarian Aid

The cargo’s nature raises a key issue as to whether, and to what extent, humanitarian aid is exempt from (naval) blockade. The Newport Manual asserts that “According to some authors, the blockading power must, if the civilian population of the blockaded area is not adequately supplied with food and other goods essential for its survival, provide for the free passage of such goods.

Such an absolute obligation has no basis in customary international law” (para. 7.4.5). However, the Newport Manual also notes another key point concerning a blockade’s “primary purpose,” indicating “The establishment of a blockade is prohibited if it is solely intended to starve the civilian population, or solely intended to deprive the civilian population of objects essential to its survival” (para. 7.4.5) (emphasis added).

By contrast, there is much opinion—sometimes organic to the law of naval warfare’s lex specialis, sometimes drawn from analogising and seeking coherence between the law of siege on land and the law of blockade at sea, sometimes drawn from application of parallel human rights law requirements—that the blockading State “must” (as opposed to “should, where practicable”) make provision for humanitarian aid supply and/or access, even if starvation of the civilian population (whilst a consequence) is not the naval blockade’s “primary purpose.” This post cannot hope to resolve this fiercely debated and complicated question. However, it is essential to note this uncertainty as each analyst’s view on this specific matter will affect any assessment of the legality of halting the transit of humanitarian aid in a specifically naval blockade.

Moreover, this is where the 2025 expanded scope of Israel’s general blockade, if extended to the naval blockade, significantly complicates the assessment of the incident. If the naval blockade is (1) as comprehensive as the 2025 tightening seems to suggest, and (2) there is no rule mandating passage of humanitarian aid, and (3) the Israeli government’s 2025 statements are understood as imposing a policy depriving the civilian population of items essential to its survival as a way to secure the release of hostages, then the issue of “primary purpose” may render the naval blockade unlawful. This is not an issue this post is capable of resolving (indeed, the “primary purpose” question is one of several currently before the ICJ and the ICC in the context of Gaza).

What is clear, however, is that even if there is a naval blockade rule that requires an exemption for humanitarian aid in certain circumstances (my own view), then the blockading power is nevertheless empowered to require any vessel claiming entitlement to that exemption to submit to visit and search by the blockading State. This right is necessary so the belligerent can confirm for itself that the cargo is, in fact, what has been declared.

Indeed, this is what Israel has historically done for Gaza-destined humanitarian aid via the port of Ashdod, where inspectors would search the cargo landed at the port, sending it across into Gaza via land border crossings only if cleared (see, e.g., the Turkel Commission Report, Part I, para. 90). However, in the case of the Conscience, it does not appear that Israel made any attempt to engage in a visit of the Conscience to check her cargo.

On the other hand, if there is no issue as to the blockade’s legality given the “primary purpose” prohibition, or there is no rule related to humanitarian aid access across the blockade line that is applicable in this specific situation, then there is no requirement for visit and search because the blockade would be comprehensive as to all vessels and cargoes. This would mean the only factor the blockading State would need to assess is whether there is a perfected or impending breach of the blockade. This—as with issue 1—then brings into focus the ultimate centrality to the assessment of issue 3: The “attack.”

Issue 3: The Attack

The key conclusion that can be drawn from an analysis of the “attack” is that regardless of any of the above, the incident was unlawful when assessed narrowly against the law of blockade. This is because a belligerent may avail itself of the option to attack a neutral (or an enemy) merchant vessel which is reasonably believed to be breaching a lawful blockade only after the merchant vessel clearly resists an order to stop and subject itself to visit, thereby frustrating the belligerent’s right to employ visit, search, diversion, and capture.

This is an uncontroversial statement. Article 67 of the San Remo Manual, for example, says “Merchant vessels flying the flag of neutral States may not be attacked unless they: (a) are believed on reasonable grounds to be carrying contraband or breaching a blockade, and after prior warning they intentionally and clearly refuse to stop, or intentionally and clearly resist visit, search or capture” (emphasis added). Similarly, the Newport Manual asserts that “Neutral merchant vessels become liable to attack if engaged in any of the following activities: … Actively resisting visit, search, or capture; refusing an order to stop; or refusing to abide by military regulations imposed by a naval commander” (para. 8.6.5). Further, the Newport Manual continues, stating that, “Vessels or aircraft breaching or attempting to breach a blockade are liable to capture and condemnation or diversion. … Vessels or aircraft that resist capture or diversion may render themselves liable to attack” (para. 7.4.7).

In the case of the Conscience, however, there is no indication that Israel (assuming attribution to it) attempted to stop and visit or divert the vessel, or exercise (if justified) the right of capture. Therefore, the attacker had no right under blockade law to attack the Conscience.

Conclusion

On the facts available at this point, the attack on the Conscience on the High Seas near Malta was unlawful if based on a blockade enforcement justification. This is because the required preliminary step in enforcing a blockade against a vessel that has clearly indicated an intention to cross the blockade line is to first call upon it to heave to and subject itself to visit, or to comply with a diversion order.

Following this, the vessel and cargo in question would normally be subjected to prize jurisdiction to assess the validity of the capture and to determine condemnation (i.e., transfer of ownership to the capturing belligerent State). In terms of blockade law, a vessel’s clear refusal of an order to stop—as seems to be missing in the Conscience’s case—is necessary before the vessel’s status can shift to that of a military objective, at which point the blockading State has the option to attack.

***

Rob McLaughlin is Professor of International Law at the Australian National Centre for Ocean Resources and Security, Honorary Professor at ANU, and a Senior Fellow at the Stockton Centre for International Law at the US Naval War College. 

The views expressed are those of the author, and do not necessarily reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense. 

Articles of War is a forum for professionals to share opinions and cultivate ideas. Articles of War does not screen articles to fit a particular editorial agenda, nor endorse or advocate material that is published. Authorship does not indicate affiliation with Articles of War, the Lieber Institute, or the United States Military Academy West Point.

Photo credit: Freedom Flotilla Coalition