The cratered remains of Palestinian supply tunnels in the south of the Gaza Strip provide stark evidence of the scale of the task facing the peace-makers in the Middle-East. Burrowing under the Egyptian border, the underground passages have become a main route into Gaza for goods, fuel and, so the Israelis fear, weapons.Israel bombed them again after Palestinian militants killed an Israeli soldier, an attack Hamas said was a response to earlier Palestinian deaths. Within hours, workers were at work, rebuilding. The tit-for-tat actions came as Senator George Mitchell was calling for the shaky ceasfire to be consolidated. There have been American and European promises to help prevent Hamas re-arming through the tunnel system. With Israeli tanks still hovering near the border, a Hamas spokesman said ongoing aggression on the Palestinian people is a dangerous escalation. Israel countered that were it to crumble, it would be the fault of Hamas.