Israeli tanks, planes and ground forces have stepped up attacks on Gaza during the day as they seek to wipe out the threat of Hamas rockets. Troops have encircled Gaza city and there has been house to house fighting in the outskirts of the city and in the north of the territory. Gaza has effectively been cut in half by the incursion and aid agencies have spoken of a desperate humanitarian situation in places.Despite the ferocity of the Israeli assault the rocket attacks have continued and Hamas has issued defiant statements. At the same time intense diplomatic activity, involving European, Arab and Russian input is underway. But there seems little prospect for a ceasefire any time soon.