Israeli forces seized 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.