Israeli naval forces on Monday intercepted the Gaza-bound boat Madleen and detained 12 international activists, including prominent Swedish climate activist Greta Thunberg, as the vessel attempted to breach the longstanding Israeli maritime blockade of Gaza.

The boat was seized after ignoring multiple warnings from Israeli authorities not to proceed toward the Gaza coast, which is off-limits under the military-enforced blockade. The vessel was later towed to Ashdod Port, where the activists were handed over to Israeli police for processing and deportation, according to the Ministry of Defense.

“The blockade is in place to prevent the smuggling of weapons and protect national security,” the ministry said in a statement. “Unauthorized maritime attempts to enter Gaza are dangerous, illegal, and undermine coordinated humanitarian efforts.”

The group of activists reportedly intended the voyage as a symbolic protest against the blockade, which they claim contributes to humanitarian suffering in the coastal enclave. Among them was Thunberg, whose participation drew international attention.

Human rights organizations have condemned the blockade as a form of collective punishment, while Israeli officials argue it is a necessary measure to curb arms transfers to Hamas and other militant groups operating in Gaza.

This is not the first attempt by activists to challenge the blockade, which has been in place since 2007. Previous flotillas have also been intercepted, often leading to diplomatic tensions and international debate over the legality of the blockade under international law.