The Israel Defense Forces sent tanks a short way into the Gaza Strip for the first time since November yesterday in response to continued heavy rocket fire on southern Israel. Palestinians fired almost 30 Qassam rockets at Israel yesterday.

In addition, the IDF stationed artillery batteries along the Israel-Gaza border, also for the first time since November, though no shots were fired, and continued its aerial attacks on Gaza, killing six Palestinians. At least three of the dead were Hamas members.

The tank incursions, accompanied by infantry, took place at two locations in Gaza - the Strip's northern tip, and a ridge west of Sderot. Both incursions stayed within a kilometer of the border. Their main goal was to assist in spotting crews launching Qassams, and they are expected to remain there for a few days.

The incursions were also meant to signal to the Palestinians that continued rocket fire could lead to a major ground operation in Gaza. Thus far, the government has not approved any more substantial ground operations, but the IDF believes that if the Qassam strikes result in heavy casualties, this decision could change.

The cabinet will meet on Sunday to decide whether to escalate the military response.

A senior army officer expressed satisfaction yesterday over the government's decision to allow the limited ground incursion, as well as the decision to resume assassinations of Hamas operatives. The army's basic approach remains unchanged, he said. It wants to avoid escalation or intervention in the internal Hamas-Fatah clashes. However, he added, if the rocket attacks on Sderot continue, escalation may be unavoidable, and the army must prepare for this.

Altogether, the IDF conducted five aerial strikes yesterday, and such strikes are expected to continue in the coming days. The first one targeted the Gaza City headquarters of a Hamas force, killing one Hamas member and wounding about 25. Shortly afterward, the Air Force fired a missile at a car in Gaza City, killing a senior Hamas operative and seriously wounding another. The third strike, again in Gaza City, hit a guard post near a Hamas office building, killing a third Hamas member.

Yesterday evening, the Air Force fired a missile at a car in Rafah, which the IDF claims was carrying the launch crew that had fired rockets at nearby Kerem Shalom shortly before. However, Palestinian sources claim that the strike killed a father and his two sons while they were riding on a garbage truck.

Meanwhile, the Fatah-Hamas clashes continued despite the latest cease-fire, killing at least three people in Gaza - one from Hamas and two from Fatah - and causing Palestinian Authority Chairman Mahmoud Abbas to cancel a planned visit to the Strip. Altogether, at least 44 Palestinians have been killed since the fighting began on Sunday.

The clashes have intensified the disagreement in Israel's security establishment over the balance of forces between Hamas and Fatah. While the IDF believes that Hamas is winning the battle against Abbas' forces - with some even saying that Fatah is finished as a significant fighting force in Gaza - other defense officials say the army's assessment ignores the facts.

An evaluation of Tuesday's Hamas-Fatah clash at the Karni Checkpoint prepared by Western security officials argues that Fatah forces preformed well against a rival that was better armed, better trained and numerically superior.

Consequently, these officials have asked Israel to give Abbas the tools he needs to fight Hamas - first and foremost, the ability to pay his security services' salaries.

Israel's security establishment, however, is still divided over whether to do so, with opponents arguing that Fatah has already lost in any case. Hence a more optimistic assessment of Fatah's performance could increase Israel's willingness to help Abbas.

Though several Arab states have promised Abbas money, only the United Arab Emirates has delivered.

On Tuesday, some 500 members of Abbas' Presidential Guard re turned to Gaza from Egypt, where they had undergone training. According to Israeli defense sources, they did not enter with Israel's approval, and it is not clear if they brought their personal weapons with them.