Israel said Wednesday it launched a limited ground operation in northern Gaza to retake part of a corridor that bisects the territory, and the country's defence minister warned that the army plans to step up the attacks that shattered a two-month ceasefire "with an intensity that you have not seen. The military said it had retaken part of the Netzarim corridor, which bisects northern Gaza from the south and from where it had withdrawn as part of the ceasefire with Hamas that began in January. Defence Minister Israel Katz warned Palestinians in Gaza that the army would again order evacuations from combat zones soon, and that its attacks against Hamas would become more fierce if dozens of hostages held for more than 17 months weren't freed. As Israel continued its airstrikes on Gaza Wednesday, the United Nations said an international United Nations staffer was killed and five others were wounded in a strike Wednesday on a UN guesthouse in Gaza. Jorge Moreira da Silva, head of the UN