The hundreds of subterranean passages that have fuelled Gaza's economy since its borders were hermetically sealed by Israel and Egypt in 2007 were one of the primary targets of Israel's three-week Operation Cast Lead. Now largely rebuilt in the wake of a war that destroyed much of the strip's infrastructure and agricultural land, the tunnels that provide Gaza with food, fuel, medicine and other consumer goods may have become even more crucial as an economic lifeline, the World Food Programme (WFP) says.