Several months ago, when the IDF Operations Directorate began drawing up plans for Operation Cast Lead, it took into account that winter was approaching and that bad weather would impair the air force's ability to produce new Hamas targets to hit. As a result, the army drew up a list of targets for every day of the operation that could be hit by the IAF no matter what the weather was - rain or shine. Like the first stage - the unprecedented aerial bombardment that has killed over 300 Palestinians - a ground operation, if launched, will also seek to shock and awe Hamas in a way that it has never felt before in face-to-face engagement with IDF ground forces. As can be seen from the border, the IDF has massed large numbers of Merkava tanks, artillery batteries, armored personnel carriers and D9 heavy bulldozers. Hamas is most likely expecting Israel to enter into Gaza and maintain its operations within a two-to-three kilometer distance from the border, like last year's Operation Hot Winter. To keep up the shock effect, though, the IDF will likely need to penetrate Hamas's home front and hit strategic targets from the ground like it did on Monday from the air, when it bombed the home of the Hamas rocket commander and the terror group's main R&D center. The IDF is expecting fierce resistance from Hamas during any ground operation. While over 300 Palestinians have been killed, the Izzadin Kassam military wing is still functioning and has not been dramatically affecting. While Hamas's communications and control-and-command systems were believed to have been badly hit, the IDF believes that in the coming days the group will rehabilitate that capability and be able to again transfer orders to its forces. There are reports that Iranian military experts are advising Hamas, although it is unclear if they are on the ground in Gaza or if the advice is being transmitted on-line. "This is the generation of Iran," a senior defense official said Monday. "They are better trained and better equipped than ever before." Hamas has five brigades - in the north, center, Gaza City, and two in the south - making up some 20,000 fighters. Each brigade has a commander as well as several battalions. Alongside the battalions there are Special Forces - units with expertise in rocket fire, mortar attacks, and roadside bombs, as well as commando forces. Hamas is believed to have a highly trained team of snipers in Gaza who were trained in Iran and Lebanon. They have also smuggled into Gaza advanced antitank missiles made in Russia and have manufactured some homemade RPGs as well. Hamas fighters will likely be fitted with night-vision and thermal goggles. Hamas has also built tunnels throughout the Gaza Strip. Some of them are for fighters to be able to move from one place to another without being detected, while others have been dug against IDF tanks. Some of the burrows have been filled with explosives. Others are meant to trap tanks. Hamas has also smuggled into the Gaza Strip a number of antiaircraft cannons as well as several shoulder-to-air missiles. With this in mind, the IDF will face a difficult mission on the ground in Gaza. The idea will be to keep up the momentum of striking at Hamas where it does not expect, and shocking it with the damage inflicted.