Israeli forces have struck targets across the Gaza Strip, including the offices of Hamas’s supreme leader, in response to a surprise rocket attack from the Palestinian territory.
The Israeli military also bolstered its troops and rocket defence systems in anticipation of a new round of heavy fighting with the Islamic militant group.
Israel opened public bomb shelters in most major cities and civil defence authorities cancelled sports events and public transportation in southern Israel.
The army said at least 30 rockets had been fired into Israel, as air raid sirens wailed across southern Israel late on Monday. The army said nearly all of the rockets were intercepted or landed in open areas.
“Israel will not tolerate this. I will not tolerate this,” prime minister Benjamin Netanyahu declared during a White House meeting with President Donald Trump.
“Israel is responding forcefully to this wanton aggression,” he said. “We will do whatever we must do to defend our people and defend our state.”
Late on Monday, Hamas announced that a ceasefire had been brokered by Egyptian mediators, but shortly afterwards renewed rocket fire could be heard in Gaza, setting off air-raid sirens in southern Israel.
Ahead of the Israeli air strikes, Hamas’s leadership went into hiding.
Several air strikes rocked Gaza, including an explosion that destroyed the office of Hamas leader Ismail Haniyeh. The Israeli military confirmed the bombing, saying the building had “served as an office for many military meetings”.
An earlier blast destroyed a multi-storey building in Gaza City that Israel said had served as a Hamas military intelligence headquarters.
There were no immediate reports of casualties. In both blasts, Israel fired warning shots to evacuate the buildings.
The new violence came at a time when Mr Netanyahu and his Hamas foes are in desperate situations.
The PM is in a tight race for re-election, and two weeks before the April 9 vote faces criticism from challengers who accuse him of being too soft on Hamas.
In Washington to celebrate the US recognition of Israel’s control of the Golan Heights, he was forced to cut his trip short under heavy pressure to strike back at Hamas.
Mr Haniyeh issued a statement warning Israel against heavy retaliation. He said the Palestinian people “will not surrender” and its militant factions “will deter the enemy if it exceeds the red lines”.
Hamas is facing perhaps its toughest domestic test since seizing control of Gaza from the rival Palestinian Authority 12 years ago.
An Israel-Egyptian blockade, imposed to weaken Hamas, combined with sanctions by the Palestinian Authority and mismanagement by the Hamas government, have all fuelled an economic crisis that has left Gaza with an unemployment rate above 50%.
Hamas has been leading weekly protests along the Israeli border for the past year in hopes of easing the blockade, but the demonstrations, in which 190 people have been killed by Israeli fire, have done little to improve conditions.
Last week, hundreds of Gazans protested over the dire conditions, a rare expression of public discontent against the authoritarian government.
Hamas responded with a violent crackdown, beating and arresting dozens of demonstrators and drawing rare public criticism.