In response to incendiary balloons launched from the Palestinian enclave Israeli aircraft struck Hamas sites in Gaza early on Sunday, the military said, as a recent increased in cross-border breach tests a fragile truce that ended fierce fighting in May.

Palestinian groups said on Saturday they were resuming protests at the Israel-Gaza border, aimed at pushing Israel to ease restrictions on the enclave.

The Israeli military said hundreds of Palestinians gathered along the frontier during the night, hurling explosives and burning tires.

The Israeli military troops responded with “riot dispersal means” and Gaza medics said at least six Palestinians were injured, one seriously. A few hours later, Israeli pre-dawn air strikes targeted what the military said was a Hamas weapons manufacturing complex and a tunnel it said was used by militants, after incendiary balloons were sent across the border.

There were no reports of casualties in the bombings.

An Egyptian-mediated truce ended the May conflict in which Gaza militants fired rockets towards Israeli cities and Israel carried out air strikes across the coastal enclave. At least 250 Palestinians and 13 people in Israel were killed in 11 days of fighting.

But violence has recently increased despite an Israeli announcement this month of a resumption of Qatari aid to Gaza, a decision that had been seen as bolstering the truce.