A new aid flotilla bound for Gaza set sail from Genoa on Sunday, with a dockworker warning that if communication with the flotilla is lost, port workers would immediately block all shipments to Israel.

The ships will join the Global Sumud Flotilla expedition, which departed from Barcelona on Sunday in an effort to deliver humanitarian supplies through Israel’s blockade.

Speaking at a rally on the docks of Genoa, one of Europe’s largest ports, a dockworker representing the USB union said that if communication with the flotilla were lost “even for just 20 minutes,” port workers would immediately block all shipments to Israel, regardless of their content.

 “Around mid-September, these boats will arrive near the coast of Gaza. If we lose contact with our boats, with our comrades, even for just 20 minutes, we will shut down all of Europe,” said the dockworker, a video of whom has circulated widely online and in Italian media but who has not been identified.

“From this region 13 to 14,000 containers leave every year for Israel, not a single nail will leave anymore,” he added.

The Global Sumud Flotilla is the fourth and the largest maritime challenge to Israel’s blockade this year, with 20 ships and over 300 crew, including Swedish activist Greta Thunberg and Irish actor Liam Cunningham, departing from Barcelona.

The mission comes as Gaza faces a deepening humanitarian catastrophe, with U.N. agencies warning of famine conditions across the region.

In Genoa, a food drive collected more than 300 tons of humanitarian aid. On Saturday, over 40,000 people, including the city’s mayor, Silvia Salis, joined a torchlit march through the streets in support of the mission.

“Every day I am proud to be the mayor of this city, but tonight, if possible, I am even more so,” Salis said.