But the flotilla’s well-traveled route — the Mediterranean — has gained new relevance during the current conflict as governments and relief organizations alike turn to sea deliveries to circumvent what aid groups say is Israel’s persistent obstruction of deliveries to Gaza over land.

The latest flotilla mission, which will include a cargo ship carrying more than 5,000 tons of aid, comes as global attention on Gaza’s worsening humanitarian crisis has waned, shifting to the escalating conflict between Israel and Iran. Apparent Turkish sensitivities over whether to allow the ships to depart has caused organizers to hedge on when exactly the voyage, which was scheduled to begin Sunday, would get underway.

The regional dynamics were “challenging,” Ann Wright, one of the flotilla organizers, said in a phone interview from Istanbul last week, where activists planning to join the maritime convoy were gathering. The mission was also at the “mercy of the port authorities” in Turkey, said Wright, a retired U.S. diplomat and former Army colonel who resigned her State Department position in opposition to the 2003 U.S.-led invasion of Iraq.

“The ships are ready,” she said.

At a news conference Friday aboard one of the ships, Huwaida Arraf, a Palestinian American human rights attorney who has joined previous flotillas to Gaza, said “our governments have thus far done nothing but we call on them to start now, to uphold their own obligations under international law, to demand that Israel allow the flotilla safe passage to Gaza.”

“We expect that Turkey will not be bought off and we will indeed sail,” she said. “Anything less than this is collaborating with the illegal siege on Gaza, and we don’t think that is what the Turkish government will do.”

The Israeli military did not immediately respond to a request to comment on the flotilla’s mission. Israeli channel N12 reported Saturday that “security preparations” had begun, including for taking over the flotilla. One of the groups participating in the voyage — a Turkish Islamic charity organization, IHH — is designated as a terrorist group by Israel. The group has denied links to terrorism.

Israel has argued for years that the naval blockade is justified to prevent weapons from reaching Hamas and other militant groups in Gaza — a policy that Arraf said was part of Israel’s “hermetic closure” of the territory that amounted to collective punishment of its population, and a war crime.

A report by a U.N. panel on the May 2010 Israeli raid called the naval blockade a “legitimate security measure,” but said that Israel’s boarding of the vessels “with such substantial force at a great distance from the blockade zone” was “excessive and unreasonable.”

Since October, Israel’s hindrance of aid deliveries by land, as well its attacks on relief organizations, have helped fuel a humanitarian crisis that has caused northern Gaza to slide into famine, according to aid officials and human rights groups.

The killing of seven World Central Kitchen workers by Israeli forces on April 1 highlighted the dangerous environment in which relief agencies operate. In the aftermath, the Biden administration warned Israel to swiftly address civilian suffering in Gaza or risk future U.S. support.

“This is a completely man-made and preventable situation,” Andrea de Domenico, the head of the U.N. Office for the Coordination of Humanitarian Affairs in the occupied Palestinian territory, said during a press briefing last week. “I think there has been a lot of effort from our side and the Israeli side to some extent to increase the volume of aid that is going to the north,” he said, while adding that significant obstacles remained.

In a six-day period this month, “41 percent of our requests for operations in the north have been denied,” he said. For Gaza’s residents, “every day is literally a struggle to survive.”

In March, President Biden announced a plan to establish a maritime aid corridor to Gaza, shortly after the United States joined other countries in dropping relief supplies by air on the enclave. Humanitarian officials said that while any additional deliveries were welcome, they were no substitute for aid delivered by trucks.

Wright said the flotilla would include a cargo ship carrying food packages, water, ambulances and medical supplies including anesthesia. “We are trying to stop the starvation,” she said. “It’s not nearly enough. It will make a dent,” she said.

Flotilla participants were conducting nonviolence training last week, in advance of the scheduled departure, she said. “We hope that we can get into Gaza,” Wright said. But they were preparing for the myriad ways they could be turned back.

Many of the governments in the region had participated in stymieing previous Gaza missions, including Greece, which stopped boats from departing in 2011. The United States had warned its citizens not to participate in the missions, and offered “very little assistance” when American activists on the flotillas were detained and then deported by Israel, she said.

If the current mission got underway, they were possibly facing an “armada,” she said, with U.S. warships stationed in the waters off Israel.

Mustafa Ozbek, the media coordinator for IHH, said the organizers had notified the Turkish government, the United Nations and other international institutions about the mission.

Dylan Saba, a 31-year old writer and attorney who was planning to travel with the flotilla, said he was joining in part because “there is an obligation for citizens of the world to act, where governments have failed, and to act in the spirit of international law.”

As a Palestinian, whose father was born in Gaza, there was a “lot of symbolic value in being able to accompany this aid that we are attempting to deliver, not just to my distant family members who are living there, but all of the Palestinians of Gaza,” he said.

“I feel very confident that this is the right thing for me to do,” he said. “But I would be lying to you if I said that I was not scared.”

Alon Rom in Tel Aviv contributed to this report.