A ceasefire announced by Hamas largely held along the Israel-Gaza border on Sunday, a day after the most intense exchange of fire between Israel and the Palestinian group since the 2014 Gaza war.

Israeli warplanes carried out dozens of airstrikes in the densely populated Gaza Strip on Saturday on what it said were Hamas military, training and supply targets, while Hamas and Islamic Jihad fired nearly 200 rockets and mortars at Israel.

Read more: Israel and Gaza's militant groups agree to ceasefire

The Israeli airstrikes wounded more than 20 people and killed two teenage boys, Palestinian health officials said, while a Hamas rocket injured four Israelis.

Hamas, which has ruled the Gaza Strip since 2007, and Islamic Jihad announced the Egyptian and UN-brokered ceasefire late Saturday. The Israeli military said its response would depend on the situation on the ground.

After the ceasefire announcement, four mortars were fired into Israel early Sunday. In response, Israeli planes destroy at least one launch site.

Israel also carried out three airstrikes later in the day on what it said were Hamas squads launching incendiary balloons and kites across the border.

Despite the minor breaches, the ceasefire largely reduced a cycle of escalation as UN envoy Nickolay Mladenov warned the two sides were on the "brink of war."

"We are one step away from another confrontation. Everybody needs to take a step back," he said in Gaza on Sunday.

Netanyahu's 'wall of steel'

Netanyahu visited the southern Israeli town of Sderot bordering Gaza on Monday, telling community leaders that Israel was engaged in a "lengthy battle." Prime Minister Benjamin Netanyahu pledged that Israel would put an end to the rocket fire and a Gaza militant campaign of sending incendiary kites and balloons across the border. Hamas will face a "wall of steel" if it keeps up its aggression against Israel, Netanyahu said. "It doesn't end in one strike," Netanyahu said. "We know we are engaged in a lengthy battle."

Israel's military said on Sunday it had deployed more Iron Dome anti-missile systems in southern Israel and around Tel Aviv. It also said a "limited amount of reserve soldiers were summoned to reinforce the Aerial Defense Command."

The Iron Dome system shot down around 30 of some 200 rockets and mortar shells fired on Saturday and Sunday.

Netanyahu has been under pressure from members of his right-wing coalition government to take a hard stance against Hamas, but the security establishment is also wary of a major escalation in Gaza at a time the Syrian army and its allies are on the offensive against rebels abutting the occupied Golan Heights.

Iranian entrenchment in Syria is now dominating Israeli security thinking, amid concerns the country could be faced with a two-front war against Hamas in Gaza, and Iran and Hezbollah in Syria. 

Read more: In Syria, rebel defeat marks 'end of revolution' 

Rolling weekly protests

Palestinians have been protesting weekly since March 30 against the dire humanitarian situation in the Gaza Strip and an 11-year Israeli blockade.

At least 141 Palestinians, including children and medical workers, have been killed by Israeli live fire during the border protests. Thousands more have been injured. No Israelis have been killed.

Israel claims the protests are organized by Hamas.

Hamas chief Ismail Haniyeh said the protests would continue and Israel must show restraint.

"Let the enemy end its aggression first and then the resistance will stop," Haniyeh said at the eulogy of the two teenagers killed in Saturday's Israeli airstrikes

The protests have largely been peaceful, but some Palestinians have thrown firebombs and grenades across the border fence.

On July 9, in response to the burning kites, Israel closed its only goods crossing into the enclave of 2 million people.

The UN condemned the decision as a "further tightening of an already-punitive and comprehensive blockade" that would worsen an already dire humanitarian crisis and amounted to collective punishment in violation of international law.  

The UN, EU and rights groups have repeatedly urged Israel to show restraint against protesters. 

cw/sms (AFP, AP, Reuters)