JERUSALEM - Prime Minister Benjamin Netanyahu visited a southern Israeli town bordering Gaza on Monday that was pummeled with rockets from the strip over the weekend and told community leaders there that Israel is engaged in a “lengthy battle.”

Netanyahu's visit to Sderot comes a day after an informal cease-fire took hold to end 24 hours of intense fighting between Israel and Gaza's Hamas militants that had threatened to devolve into all-out war.

Israel pounded Hamas targets in its most massive bombardment since the 2014 war, while militants fired dozens of rockets toward Israel that halted daily life in the area. Two Palestinian teenagers were killed in an Israeli airstrike in Gaza City, while four Israelis were wounded from a rocket that landed on a residential home in Sderot.

Netanyahu visited a local kindergarten and pledged that Israel would put an end to the rocket fire and a Gaza militant campaign of flying incendiary kites and balloons across the border that have ignited fires damaging Israeli farms and nature reserves.

Hamas will face a “wall of steel” if it keeps up its aggression against Israel, Netanyahu warned, adding however that the threat won't disappear overnight.

“It doesn't end in one strike,” Netanyahu said. “We know we are engaged in a lengthy battle.”

Hours after Netanyahu spoke, the Israeli military said planes bombarded two Hamas positions in the northern Gaza Strip in response to flaming balloons launched into Israel.

On Saturday, the Israeli military said it struck several Hamas military compounds and flattened a number of its training camps. Hamas retaliated with more than 200 rockets and mortars toward Israeli communities, it added.

After Hamas accepted an Egypt-mediated cease-fire late Saturday, the situation calmed down but flaming kites and balloons continued to drift over into Israel, with the adopting signalling a new policy of striking back immediately.

The government is under pressure from local communities to show zero tolerance to this new threat, and Netanyahu told local leaders that he had instructed the military to halt it completely.

“There is no such thing as a cease-fire that does not include the flaming kites and balloons,” he said. “If this is not understood through my words, it will be understood through the military's actions.”

On Sunday evening, the military announced that following a “situation assessment” it reinforced its Iron Dome batteries in central Israel and in the country's south and called up a small number of reserve army soldiers. The Iron Dome shot down more than 20 projectiles over the weekend.

With Israel focused on efforts to prevent Iran from establishing a permanent military foothold in neighbouring Syria, it has been wary of escalating violence in Gaza. But the extensive offensive appeared aimed at signalling to Hamas that it was unafraid to engage if necessary.

The flare-up came after months of near-weekly border demonstrations organized by Hamas aimed in part to protest the Israeli-Egyptian blockade of Gaza. Over 130 Palestinians have been killed by Israeli fire since the protests began on March 30.

Israel says it is defending its sovereign border and accuses Hamas of using the protests as cover for attempts to breach the border fence and attack Israeli civilians and soldiers.