In the Mediterranean Sea, on Thursday 2 October 2025, the Israeli Navy intercepted a 45-boat ‘Sumud Flotilla’ that sailed from Spain intending to breach Israel’s blockade on Hamas in Gaza. The flotilla was an expensive expression of confrontational political activism using yachts and ships. You could compare it to throwing paint from Lamborghinis and then ramming them into security checkpoints.
International law is used ever more frequently as a rhetorical tool in the war of words that accompanies the Hamas-Israel war. “You are not allowed by international law to stop us. Therefore, we do not comply with your request,” announced the Sumud Flotilla spokesperson, Thiago Ávila, when asked by the Israeli Navy not to proceed further.
Israel and Egypt have each imposed blockades on Gaza since Hamas seized control over Gaza in 2007. The Israeli naval blockade against Hamas is legal under international law, which permits naval blockade against an enemy during armed conflict. There was undeniably an armed conflict in progress at the time of interception of the Sumud Flotilla.
The 1909 London Conference produced a declaration that codified the law applicable to naval blockades in armed conflict at sea that has become accepted as customary international law and has been elaborated on for current times in the 1994 San Remo Manual. A blockade applies against supplies to the enemy by neutral country civilian vessels. Effective enforcement, rather than a ‘paper blockade’, is essential and specifically includes capture of vessels that intend to breach the blockade, including interception on the high seas at a far distance from the blockaded coast. The Sumud Flotilla had clearly announced its intention to breach the blockade.
Extrapolating principles of civilian protection from the First Additional Protocol to the Geneva Conventions, if other avenues of relief for the blockaded civilian population are unavailable, then vessels bringing humanitarian relief under a neutral flag can be excepted from the blockade. However, their passage is subject to their inspection and clearance by the blockading power. Israel offered to deliver the humanitarian relief or arrange for third parties to do so, as discussed below, but the Sumud Flotilla refused any form of cooperation.
To enforce its blockade, Israel operates an exclusion zone out to 150 nautical miles from the Gaza coast, which is located in international waters. The Sumud Flotilla was intercepted at 90 nautical miles, also in international waters, as specifically permitted under international law.
Smaller flotillas were intercepted in June and July this year and an additional flotilla on its way from Italy is also expected to be intercepted. The large Sumud Flotilla was more closely comparable to the large Mavi Marmara flotilla in 2010, led by a Turkish Islamist NGO, HIH, that also sought to breach and end the naval blockade against Hamas. When the under-armed and under-prepared Israeli Navy intervened at sea and boarded the Turkish flotilla, those on board the Mavi Marmara attacked and injured the Israeli boarding party, even knocking unconscious and seizing Israeli Navy Seals. Pistol shots were then fired by the Israelis and nine jihadists were killed.
In a 2011 report on the Mavi Marmara incident for the UN Secretary-General, an authoritative UN commission of inquiry, the Palmer Committee, headed by former prime minister of New Zealand Sir Geoffrey Palmer, an expert on international law, found that the Israeli blockade of Hamas was legal under the international laws of armed conflict. The report concluded that Israeli enforcement actions on the Mavi Marmara resulted in disproportionate harm.
In the case of the Sumud Flotilla, according to Italy’s Foreign Minister, Antonio Tajani, Israeli Foreign Minister, Gideon Saar, assured him that violence would be avoided. Learning to mitigate risks of violence from the Mavi Marmara interception experience, preparation for and engagement with the blockade-busters was extensive. Even though the operation was much more complex due to the large size of the fleet, harm was negligible. Hence, the evidence indicates that the interception operation was compliant with international laws that require minimisation of harm to civilians within and armed conflict.
From the outset, the Sumud Flotilla was controversial for its provocation against a legitimate naval blockade and its negligible humanitarian role. ‘Sumud’ popularly means resistance in Arabic, so its name signifies that its primary function was political. The Sumud Flotilla activists’ mass and social media efforts were designed to maximise publicity against Israel. The intent was to oppose Israel’s blockade of Hamas and in effect to support Hamas.
The Israeli Foreign Ministry documented ties between Hamas and its foreign public relations arm, the Palestinian Conference for Palestinian Abroad, with the Sumud Flotilla. The Ministry published a letter signed by the political chief of Hamas in 2021, calling for Hamas and PCPA unity, and it also published a list of PCPA members obtained from Hamas, “some of whom are high-ranking, well-known Hamas operatives.” The PCPA leader in the UK has been a blockade-busting flotilla organiser for over 15 years. Another PCPA member is the CEO of Cyber Neptune in Spain, “a front company in Spain that owns dozens of the ships participating in the ‘Sumud’ Flotilla” that “are secretly owned by Hamas.”
To protect their activists, one Spanish and two Italian naval frigates accompanied the flotilla, up to 150 nautical miles from the Levantine coast, but stressed that they would not engage with the Israeli Navy, which would have been military action on behalf of Hamas. Both appealed to flotilla activists to accept alternative means for the delivery of the aid that they carried, as offered by Israel.
Israel offered various means multiple times to deliver the Sumud Flotilla’s aid. It offered for the vessels to unload at the port of Ashdod in Israel, or in Greece or Cyprus, or to use the good offices of the Holy See of the Catholic Church instead of Israeli authority. All of these offers were refused by the flotilla organisers. Only the breach and end of the blockade against Hamas could suffice.
Humanitarian aid carried by the flotilla was very minor. The aid carried on board was said by the activists themselves to be ‘symbolic’. There was not much room for it anyway among the 500-600 activist passengers. For a quick comparison, in September, Israel facilitated the entry of 5,042 trailer trucks carrying humanitarian food and medical supplies amounting to hundreds of tons. Aid was the Sumud Flotilla’s least effective function and least important purpose, essentially a fig leaf to cover the activists for taunting of the Israeli Navy and baiting of (Jewish) Israelis.
The Sumud flotilla cost cashed-up anti-Israel activists and supporters months in preparation, weeks of sailing, hundreds of thousands of communications on social media, and millions of dollars. But it sure was a media frenzy and lots of fun. For example, from France, politicians Marie Mesmeur and Rima Hassan and actress Adele Haenel came along, and, from Malaysia, singers and actresses Heliza and Hazwani Helmi, Zizi Kirana and Ardell Aryana, were on board. Of course, climate campaigner Greta Thunberg was on hand too, seeking her second deportation, and Susan Sarandon RSVP’d her regrets and best wishes.
Interception of the Sumud Flotilla was not a case of Israeli breach of any international law. The blockade is clearly legal under the international laws of armed conflict at sea and the complex interception at sea was flawlessly compliant with international humanitarian law. This was a case of cash-rich social radicals and fashionable keffiyeh flunkies out cruising in the maritime equivalent of Lamborghinis, videoing selfies, mouthing off and pushing against the boundaries of law and order. The edited film footage is simply fabulous.
Gregory Rose is Professor of International Law the University of Wollongong and Senior Fellow with The Hague Initiative for International Cooperation.