Operation Summer Rains was to enter into its second phase this morning, with the incursion of a large contingent of Israel Defense Forces troops into the rubble of three evacuated northern Gaza settlements: Elei Sinai, Dugit and Nissanit.

The cabinet approved the incursion yesterday in response to the firing of a Qassam rocket on the center of Ashkelon on Tuesday. Troops are preparing to remain in the three evacuated settlements for at least several days and capture several kilometers of land deep in Palestinian territory, in an effort to make it difficult for Palestinians to fire additional Qassam rockets at Ashkelon.

In contrast, the other IDF activity in Gaza over the past week is part of the first phase of Operation Summer Rains, which is intended to secure the release of Corporal Gilad Shalit and halt Qassam fire on Sderot. More than a week after the operation began, not only is the abducted soldier still being held captive, but the rocket fire has spread from Sderot to Ashkelon.

The commanders of the operation were concerned last night over the risk to troops: They presume the Palestinian organizations have higher-quality anti-tank weaponry and explosives than they had before last summer's disengagement. If the IDF sustains losses, the Palestinians will have created a new deterrent balance, making it difficult for Israel to decide on additional ground operations.

The relatively large forces being sent into the northern section of the Strip are meant to make it difficult for Qassam-launching cells to approach the northern end of Gaza and attack Ashkelon. However, it is not yet clear exactly how long the troops will remain in Gaza or whether they are creating a long-term "security strip."

But the longer the incursion continues, the greater the risk to the lives of the soldiers and the greater the potential that Palestinian civilians will be mistakenly attacked. And as soon as the troops leave, Palestinians are likely to renew the rocket fire on Israel.

The ministers who approved the north Gaza operation are aware of the risks, just as the officers who recommended the operation are aware of them. However, they see Israel and Hamas as being close to war and consider it likely that harsher steps will need to be taken.

The authorities are discussing renewing assassinations of Palestinian leaders - not just leaders of the Hamas military wing, but the group's political leaders as well. The IDF sees the suspended talks on Shalit's release and the rocket attack on Ashkelon as likely justification for renewing assassinations.

The argument over Israel's assassination policy has lasted even longer than the second intifada. Assassinations have not put an end to terrorism, and every assassinated terror leader has been replaced rapidly. Even when Hamas political leaders were attacked, the group's popularity suffered no damage. On the other hand, assassinations have contributed to a change in Hamas tactics, as seen in their 2003 agreement to a cease-fire (hudna) and their 2005 agreement to a security lull in the territories (tahadiyeh).

Hamas is engaged in calculating costs and benefits. For instance, the killing of its leaders is comparable to the collapse of the government and Hamas' loss of power, but it is expected to increase public sympathy.

In addition to the latest incursion, meanwhile, the IDF is also operating in three other sectors of the Strip, two of which - the Erez crossing and Beit Hanun areas - are also in northern Gaza. The third area is the Dahaniyeh airport in southern Gaza. The troops have been searching near the fence surrounding the Strip for explosives and tunnels, such as the one the Palestinians used in the Kerem Shalom attack that led to Shalit's abduction, and have not encountered stiff opposition.

Also in Gaza, the Israel Air Force bombed the Palestinian Interior Ministry early yesterday, lightly wounding three Palestinians. The IAF also bombed two other Gaza targets: a school identified with Hamas, which the army said is used for terror activity, and a Hamas camp near Khan Yunis. There were no injuries in either air strike.

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