What we do we know from previous conflicts in Gaza? Fighting between the Israeli military and Hamas has tended to follow a similar pattern, with ground incursions launched over the years on different scales usually preceded by a heavy barrage that targets areas and locations used by the Israelis to approach. Israel has also made heavy use of air power and shelling from land-based artillery and naval gunboats in the first phase of campaigns to target what it says is Hamas’s military infrastructure, including government buildings, police stations, coastal installations, training facilities and the homes of senior officials. But while Israel has a huge advantage in terms of the size of its military, technology, weapons systems and logistics, Hamas has adapted considerably over the years to take advantage of Gaza’s dense urban environment. How will geography influence any fighting? The geography of Gaza is limiting for Israeli operations and because of that the Israel Defence Forces tend to use the same approach routes. There are rural areas of farmland next to the Erez crossing in the far north of Gaza, around Bureij south of Gaza City where there is ridge line overlooking central Gaza, and to the east of Khan Yunis in the south where tanks and armour can move more easily and take up firing positions. Another access point is around the Philadelphi Route near Rafah in the far south. Israel has in the past used positions overlooking central Gaza to try to cut communications between Gaza City and the south and elsewhere to carve up the area. Hamas and other factions in Gaza are aware that these are routes that Israeli forces can use and will often have their first lines of defence in these areas, which have been the scene of heavy fighting in the past. As the sandy countryside turns to urban areas, the terrain gets more difficult for Israel. High rise residential blocks in places such as Jabaliya and Beit Lahia overlook the northern approaches towards Gaza City while the main north-south road is bordered by industrial areas Hamas has used defensively in the past. The terrain in the centre of Gaza and east of Khan Yunis is more open, but villages and taller buildings along the approach roads and have provided cover for Hamas. Will the Israelis go into the main cities? Israeli forces have experienced heavy assaults attempting to advance into the major urban centres. Hamas and other factions have anti-tank mines and anti-tank guided missiles which they have used effectively along with mortar fire. On one night of fighting in the built up area of Shujeiya during the 2014 war, Israel lost 13 soldiers in an ambush that involved an anti-tank mine and machine-gun fire. While the Israeli military does have experience of fighting with armour in Palestinian cities, not least on the West Bank during the second intifada, Hamas is now believed to have a large stockpile of Kornet anti-tank missiles which have been used effectively, including by Hezbollah in Lebanon, against Israeli main battle tanks. The group has also developed munition-equipped drones of the kind used widely in Ukraine which can drop bombs on vehicles and troops, a new threat. How will Hamas respond? Hamas has years of experience fighting the Israeli military and has become an adaptable and effective urban force. It has a core of experienced combat leaders who are intimately familiar with the Israeli way of fighting, some of them Hebrew speakers who have studied the Israeli military in depth. A major problem for Israel in any attempt at a ground offensive is that it will have to confront prepared Hamas positions, including combat tunnels developed extensively over the years and in some cases equipped with communication systems. Where Hamas’s tunnel networks were once rudimentary, its engineers now have considerable experience in building hardened and well-hidden underground locations to use as command centres and for deploying fighters from. And while Israel once had a clear surveillance advantage over Gaza, cheap and readily available civilian drones acquired by Hamas have levelled the playing field, allowing them to observe Israeli lines of approach. Can Israel reconquer Gaza? While Israel probably does have the military capacity and the will after Saturday’s attack, the cost is likely to be heavy for the Israeli military and Palestinian civilians and with risk to Israeli hostages being held in the territory. A full re-occupation of Gaza would be profoundly challenging and probably beyond Israel’s capacity to administer in the long term, which suggests that if Israel does go for a full invasion its objective is more likely to be a comprehensive defeat of Hamas.