The IDF attacked a manned Hamas position in Gaza early yesterday morning, for the first time since operation Cast Lead ended in January 2009, leaving three members of the organization dead and several injured.

The attack came following information that the rockets and mortar shells fired into Israel in the past few days had been launched by order of Hamas.

The Israel Air Force attacked seven Hamas targets in total, including four tunnels the army said were meant for launching assaults across the border with Israel, a training facility and weapon dumps.

The attack followed the firing of seven mortar shells from Gaza at an Israeli border community. A Qassam rocket was fired just before 8 A.M. in the direction of an Israeli kibbutz right after the attack. It landed about 20 meters away from a daycare center, leaving four Israelis lightly injured and four in shock. A fifth Israeli, a teenage girl, was injured by shards of broken glass.

Around noon, the IAF attacked a Hama target in the south of the strip in response.

"There were about 10 children in the center when the rocket fell," Ronit Gil, an employee of the daycare center, told Haaretz. "I immediately got out of the car and ignored the sirens so I could be with the children. I brought them all together and kept them busy."

Gil described the mood in the border communities as tense in recent weeks and said that the children are once again practicing running to reinforced spaces during rocket sirens. "The doors are always open and the children can't leave the daycare center. We're very careful about that," Gil said.

Yair Farjoun, the head of the Hof Ashkelon regional council visited the site where the rocket landed. He said that he believes "in the IDF's ability to carry out the action necessary to stop the rocket fire."

Fighting near the Gaza Strip appears to be escalating, with 30 mortar shells and rockets fired at Israel in the past 10 days alone.

IDF sources told Haaretz that since operation Cast Lead, most of the attacks had been launched by smaller Palestinian groups opposed to Hamas, such as the World Jihad and the Army of Islam. By contrast, the recent attacks were carried out by larger paramilitary organizations acting in cooperation with Hamas, among them the Popular Resistance Committees and the Palestinian Jihad.

These organizations had largely avoided carrying out attacks on Israel in the past two years, under orders from Hamas.

Officers in the IDF Southern Command told Haaretz they believe recent rocket fire and shelling indicated that Hamas is trying to test Israel's limits. They said they do not believe Hamas is interested in a real escalation, and therefore, it has avoided using its own members in the attacks.

The reasons for the escalation are varied, according to observers, who said they could be part of an attempt to mark the two-year anniversary to operation Cast Lead, or alternatively, they reflect a desire to let off "steam" after months of relative quiet and frustration with the lack of progress in negotiations over prisoner exchange and over Hamas-Fatah reconciliation.

The IDF believes that Hamas is still trying to rearm and restore its military capabilities, damaged in operation Cast Lead, and is therefore not interested in provoking too harsh an Israeli response. Nevertheless, the army said it is aware of major improvements in the organization's capabilities, including a recent shipment of anti-tank and anti-aircraft missiles. These missiles were already in the organization's possession during Cast Lead, but Hamas lacked the knowledge and training to use them.

In the two years since, the army said, members of the organization have left, via the Sinai tunnels, to training camps in Syria and Iran, and foreign experts have entered Gaza. This became apparent two weeks ago, when an advanced Russian "Cornette" missile hit and penetrated a Mark III Merkava tank. The missile failed to explode and no casualties were reported, but the incident prompted the IDF to deploy armored division 401, which uses Mark IV tanks equipped with the anti-missile defense system "Windbreaker."

"This is a heavy rocket, one of the most dangerous ones in the field, which has been used against the IDF in the Lebanon War," the Chief of Staff told the Knesset Foreign Affairs and Defense Committee yesterday. He said that the IDF detected a desire among the Palestinian paramilitary organizations to change the rules of the game along the borders of the Strip, especially where IDF forces operated several meters into the Palestinian territory.

The IDF does not plan any moves at the moment beyond deploying more advanced tanks along the Strip, but the army is preparing for an extended period of escalation.