If ordered into the Gaza Strip, IDF Ground Forces expect to encounter Hamas cells with anti-tank missiles, heavy urban combat, subterranean warfare, and other challenges. "This is the combat that characterizes a terror organization," the source said. The IDF has maintained large numbers of Ground Forces on the Gaza border.IDF Brigade commanders would have a high degree of independence if ordered to enter the Gaza Strip.Hamas planned to employ bomb-filled tunnels to facilitate large-scale killing sprees and kidnapping attacks on the border, according to Israeli security officials.Hamas will try to prove that an Israeli ground offensive will not have an impact on its ability to fire rockets, though its chances of achieving this remain decidedly low. Only a ground maneuver can truly deal with the growing threat of tunnels that straddle the border, officials believe.Addressing Hamas's use of the Palestinian population as a human shield, the senior source said there are over a dozen Hamas brigade commanders who are hiding within the Gazan civilian population, preventing the IDF from striking them. Hamas commanders use messengers who pass along written notes, he added."From our perspective, we did not attack homes," a senior security source said Tuesday, looking back at recent IAF strikes. "[We attacked] only operational infrastructure. We understood what every Hamas commander has in his infrastructure. From the moment there is an operational infrastructure there, it ceases being a home," said the source. T he systematic targeting of such nerve centers has negatively affected the performance of Hamas brigades. Additionally, Israeli targeted assassinations, based on swift sensor to shooter cycles, in which IDF control centers coordinated air strikes after identifying terrorist operatives in the field, has resulted in some 100 casualties among Hamas and Islamic Jihad since the start of the operation.Meanwhile, some 20,000 Palestinians civilians have heeded Israeli calls and evacuated Bet Lahia in northern Gaza, where a concentration of heavy rockets are concentrated and fired at Israel from.Looking ahead, the source said there is internal disagreement within Hamas over how to proceed next.Hamas is searching for guarantees that will enable it to pay its 43,000 members some 20 million dollars a month. Senior security sources said that without a financial solution for Hamas, no truce will stabilize the situation.Before the current operation, Hamas was producing some 30 medium-range rockets a month – more than it was able to smuggle before Egypt closed off smuggling tunnels linking Sinai to Gaza.The source said some 60% of rocket production sites have been destroyed by Israel in the current operation. This won't stop Hamas from rearming in the future, but will slow down its production rate, the source argued. Much of what is used to construct the rockets is dual-use material, which cannot be kept out of Gaza, he added.Before the start of the operation, Hamas had around 350 mid-range rockets that can reach greater Tel Aviv. The IDF has destroyed a third – 3000 – of Hamas's rocket arsenal, made up of 9000 rockets.Hamas and Islamic Jihad have fired around eight long-range rockets, targeting northern Israel, so far.