TEL AVIV (Reuters) – Israeli warplanes bombed Hamas sites in Gaza in response to incendiary balloons launched from the Palestinian enclave that caused brush fires in southern Israel, its military said early on Tuesday.

There were no immediate reports of casualties in the air strikes that targeted what the military said was a weapons production facility and a rocket launch site belonging to Hamas, the Islamist group that rules Gaza.

Since an Egyptian-mediated ceasefire halted 11 days of Israel-Hamas fighting in May, Gaza militants have sporadically sent balloons laden with incendiary material into Israel, drawing Israeli strikes on Hamas facilities.

Palestinians say the balloons aim to pressure Israel to ease restrictions on Gaza and permit aid to reach the territory. Balloons launched Monday set off fires in Israeli fields along the Gaza border, Israel’s Fire and Rescue Service said.

Cross-border violence has spiked despite an Israeli announcement last week of a resumption of Qatari aid to Gaza, a move that had been seen as bolstering the fragile truce.

Confronting Gaza protesters burning tyres and throwing explosives along the border on Saturday, Israeli troops shot and wounded 41 Palestinians, critically injuring two, medics said. Palestinian gunfire seriously wounded an Israeli soldier, the military said.

Days before Saturday’s violence, Gaza militants launched a rocket towards Israel that was shot down by its Iron Dome anti-missile system, in the first such rocket attack since the May 21 ceasefire.

More than 250 Palestinians and 13 in Israel were killed in the May conflict, during which Gaza militants fired rockets towards Israeli cities and Israel carried out air strikes across the coastal enclave.

Israel keeps Gaza under blockade, tightly restricting movement out of the territory that is home to 2 million Palestinians. Egypt also maintains restrictions on the enclave. Both cite threats from Hamas for the restrictions.