A full-scale Israeli military operation in Rafah could lead to a slaughter and cripple life-saving humanitarian work throughout the Gaza Strip, the UN Office for the Coordination of Humanitarian Affairs (OCHA) said on Friday. The UN, governments and aid agencies have been appealing to Israeli authorities for weeks to spare Rafah, but a ground operation in Gaza's southernmost city, where more than 1.5 million people are at risk, is looming on the immediate horizon.