Israeli forces stopped a Gaza-bound aid boat and detained Greta Thunberg and other activists who were on board early Monday, enforcing a longstanding blockade of the Palestinian territory that has been tightened during the war with Hamas.

The activists had set out to protest Israel’s ongoing military campaign in the Gaza Strip, which is among the deadliest and most destructive since World War II, and its restrictions on the entry of humanitarian aid, both of which have put the territory of some 2 million Palestinians at risk of famine.

The Freedom Flotilla Coalition, which had organized the voyage, said the activists were “kidnapped by Israeli forces” while trying to deliver desperately needed aid to the territory.“The ship was unlawfully boarded, its unarmed civilian crew abducted, and its life-saving cargo—including baby formula, food and medical supplies—confiscated,” it said in a statement.

Israel’s Foreign Ministry cast the voyage as a public relations stunt, saying in a post on X that “the ‘selfie yacht’ of the ‘celebrities’ is safely making its way to the shores of Israel.”

It said the passengers would return to their home countries and the aid would be delivered to Gaza through established channels. It later circulated footage of what appeared to be Israeli military personnel handing out sandwiches and water to the activists, who were wearing orange life vests.

Thunberg, a climate campaigner, was among 12 activists aboard the Madleen, which set sail from Sicily a week ago. Along the way, it had stopped on Thursday to rescue four migrants who had jumped overboard to avoid being detained by the Libyan coast guard.

Rima Hassan, a French member of the European Parliament who is of Palestinian descent, was also among the volunteers on board. She has been barred from entering Israel because of her opposition to Israeli policies toward the Palestinians.

Israel imposed its blockade on Gaza, with Egypt’s help, after Hamas, the Islamic militant group, took over the coastal strip in 2007. Israeli officials have said the blockade is necessary to prevent weapons from being smuggled into the enclave.

Conditions in Gaza have worsened dramatically in the 20 months of war since the deadly Hamas-led attack on Israel in October 2023. Israel recently barred the entry of humanitarian aid into the territory for 80 days, bringing the population to the brink of famine, according to international aid organizations. It has since supported an aid delivery system that has been marred by violence and shunned by humanitarian groups.

Israel’s threats

Israel’s defense minister, Israel Katz, said Sunday that he had instructed the country’s military to prevent the vessel from reaching Gaza.

In a blunt statement, he said, “To Greta the antisemite and her friends, propagandists for Hamas — I say clearly: You would do well to turn back, because you won’t get to Gaza. Israel will act against any attempt to breach the blockade or aid terrorist organizations by sea, air or land.”

Thunberg has been an outspoken opponent of Israel’s blockade and its conduct of the war.

“We are doing this because, no matter what odds we are against, we have to keep trying,” Thunberg said last week. “Because the moment we stop trying is when we lose our humanity. And no matter how dangerous this mission is, it’s not even near as dangerous as the silence of the entire world in the face of the livestreamed genocide.”

Earlier aid attempts

Israel’s military has blocked past attempts by pro-Palestinian activists to bring aid to Gaza by sea, including by force. In 2010, nine passengers aboard the Mavi Marmara, part of a flotilla carrying aid from Turkey to Gaza, were killed in an Israeli commando raid, stirring international outrage and damaging Turkish-Israeli relations. A 10th passenger died from his wounds years later.

An attempt last month by Freedom Flotilla to reach Gaza by sea failed after another of the group’s vessels was attacked by two drones while sailing in international waters off Malta. The ship was rocked by explosions off the coast of Malta, setting it on fire.

This report includes information from the New York Times.