Greta Thunberg and "Game of Thrones" actor Liam Cunningham are among 12 activists aboard the Madleen, which is operated by the Freedom Flotilla Coalition, that is on its way to Gaza.

Israel's Katz said he instructed the military to "take whatever measures necessary" to stop the ship carrying Thunberg and other activists.

Israel won’t allow a flotilla of activists — including Swedish environmentalist Greta Thunberg — sailing toward the Gaza Strip to reach the coastal enclave, Defense Minister Israel Katz said on Sunday.