"We are preparing for a campaign against Hamas, which will not end within a few days," Defence Minister Moshe Yaalon said

Israel launched an offensive against the Gaza Strip Tuesday, conducting a series of fresh airstrikes in response to increasing rocket attacks by Palestinian militants.

There have been more than 120 Israeli airstrikes in the coastal enclave, according to Palestinian sources, while hundreds of rockets and mortar shells have landed in southern Israel.

It is the first time Hamas has claimed responsibility for rocket fire into Israel since November 2012, when Israel launched its last major offensive against Gaza.

“We are preparing for a campaign against Hamas, which will not end within a few days,” Defence Minister Moshe Yaalon said.

“We are prepared to expand the campaign using every means at our disposal to continue to strike at Hamas,” he warned.

According to Palestinian medics, 30 people were injured in the latest airstrikes and four homes, belonging to militants, were destroyed.

Residents said they received telephone calls telling them to evacuate the homes several minutes before the buildings were hit.

Israeli military spokesman Peter Lerner said the offensive, named Protective Edge, could grow into a “ground mission if required.” Reserve forces were being called up in preparation.

The escalation in violence came on the heels of growing tensions in the West Bank, especially since the abduction and murder of three Israeli teens, which Israel blamed on Hamas, though the group denies responsibility.

Hundreds of Hamas activists were arrested and its institutions were shut down in the West Bank in response.

A Palestinian teen was then burned alive last week, further inflaming tensions. Israeli police arrested six Jewish suspects, believed to be radicals seeking retribution.

Hamas claimed responsibility for the rocket fire, which in the recent past had been attributed to smaller groups, after seven fighters died in a tunnel collapse, which the group blamed on an Israeli airstrike.

“The Palestinians today are carrying out a struggle against a Zionist government which should be referred to the International Criminal Court for the crimes it is committing against the Palestinians,” Ali Barakeh, Hamas’ spokesman in Lebanon, said.

Barakeh urged Arab nations to side with the Palestinians, amid growing schisms among countries in the region as a result of the Arab Spring.

Izat al-Resheq, a senior Hamas leader, wrote on his Facebook page that the militant movement was “ready to fight to the end” if Israel launched “a new war” on the Gaza Strip.

Sirens have been going off regularly in southern Israel since last week, warning residents to urgently seek shelter from the barrage of rockets.

Schools, kindergartens and summer camps were shuttered if they were within a radius of 40 kilometres of the Gaza Strip. Police banned any gatherings or demonstrations of more than 300 people in the region.

“This is a very difficult situation that requires real mental strength,” said Hanna Tal, a social worker in the Shaar HaNegev regional council, which borders Gaza.

“For the past week and a half, there are constantly mortars and rockets and this really stresses the people out,” Tal told dpa, noting that more and more people are reaching out for help to deal with trauma.

Rioting, meanwhile, resumed in and near Arab towns in northern Israel after dark, in response to the July 2 abduction and slaying of 16-year-old Muhammad Abu Khdair from East Jerusalem.

The protesters burnt tires and threw stones at police and at least one civilian bus. Some 24 were arrested, a police statement said Tuesday morning, bringing the total of arrests in six consecutive nights of protest to 107. Arrests were also made in Jerusalem.

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