The mission of the Global Sumud Flotilla, currently sailing from Barcelona, Genoa, and other ports to deliver humanitarian aid to Gaza, raises a range of legal issues linked to the likelihood of Israel intervening in international waters to block the vessels and arrest those on board.
International law is straightforward around two principles: the freedom of navigation on the high seas, and the protection of civilians in situations of armed conflict, such as the one unfolding in Gaza.
The 1982 UN Convention on the Law of the Sea (Montego Bay) establishes that freedom of navigation on the high seas must be respected. This principle, which has the status of a globally applicable norm regardless of treaty ratifications, grants exclusive jurisdiction to the state where the ship is registered, including over unlawful acts committed on board. Israel’s allegations of “terrorism” against flotilla activists are unsubstantiated and, in any case, do not change the allocation of jurisdictional competence.
Any intervention by Israeli authorities on the Global Sumud Flotilla in international waters would thus constitute a breach of international law against the states whose flags the ships fly, as well as those of the foreign nationals on board, should they be arrested.
In its capacity as an occupying power, Israel also bears well-known responsibilities under international humanitarian law, including key obligations under the Fourth Geneva Convention on the Protection of Civilians in Occupied Territories. The prohibition of collective punishment of civilians and the prohibition of starvation of civilians as a method of war, for example, are critical for evaluating the famine currently unfolding in Gaza. Regardless of any international crimes that may be occurring, the key point is that no blockade can excuse the causing of disproportionate harm to civilians or the failure to comply with the obligation to allow the delivery of humanitarian aid.
Historically, Israel has refused to accept the application of international humanitarian law and international human rights law in Gaza, the West Bank, and East Jerusalem. Yet this position has been consistently dismissed by the International Court of Justice and international legal scholars, since it has long been accepted that a situation of occupation still requires the occupier (whatever the cause of the occupation) to abide by human rights and humanitarian standards.
The Global Sumud Flotilla inevitably recalls the 2010 attack on the Mavi Marmara, a humanitarian vessel bound for Gaza on a similar mission. That raid left nine activists dead and more than fifty injured. The international fact-finding mission established by the UN Human Rights Council to investigate the incident concluded that Israeli forces had committed serious violations of international humanitarian and human rights law both during the interception in international waters and during the detention of passengers in Israel prior to deportation. It also crucially noted that Israel’s naval blockade inflicted disproportionate damage upon the civilian population in the Gaza Strip.
As noted in an earlier analysis in 2023, Israel’s presence in the occupied territories cannot be extended indefinitely, nor can Palestinian self-determination (separate from the conflict with Hamas) be subject to legal conditions by Israel as the occupying power. The International Court of Justice confirmed this principle in a 2024 advisory opinion. The initiative of the Global Sumud Flotilla will neither end the occupation nor achieve Palestinian self-determination. It is ultimately designed to pressure Israel to reconsider its policies on the protection of civilians and to stop and prevent the famine in Gaza by securing the flow of essential supplies such as food and medicines. Even so, its chances of being successful remain to be seen. But to the extent that the initiative remains undeterred in its peaceful humanitarian objectives, international law is clear as to what needs to happen.
Cover photo: An activist shows a map while leaving on a boat, part of a civilian flotilla aiming at breaking the Israeli blockade of the Gaza Strip, in the port of Barcelona, on August 31, 2025. A flotilla carrying humanitarian aid and activists is due to leave from Barcelona on August 31, 2025 to try to “break the illegal siege of Gaza”, organisers said. The flotilla is expected to arrive at the war-ravaged coastal enclave in mid-September. (Photo by Lluis GENE / AFP)
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