Israeli ground offensive in Gaza faces physical and political risks

Military has might on its side but Hamas is prepared and the humanitarian fallout could prove costly

• Israel and Hamas at war - live updates

Israel is poised to launch a ground offensive into the northern half of Gaza, an attack that, for all the country's military superiority, is fraught with uncertainty and whose potential humanitarian consequences are grim.

The military called up 300,000 reservists on Monday to add to its 170,000-strong standing army and has been massing them near the Gaza border. Hamas, it is estimated, can count on 30,000 fighters, perhaps a tenth of the likely invasion force, and it has neither the tanks nor the air power available to the attackers.