Just days after returning from Washington for talks on the Iran nuclear threat, Israel's Benjamin Netanyahu found southern Israel hammered by rockets from Gaza, with the premier insisting the two threats are twinned.

Four days of cross-border violence in and around Gaza ended with a truce agreement early on Tuesday, putting an end to an episode which Israeli officials feared could escalate and deflect the world's attention from the main problem: Iran's nuclear drive.

Netanyahu last week held talks on the issue with US President Barack Obama, winning US assurances that Washington would ultimately be prepared to use military force to prevent Iran developing a nuclear weapon.

"Our commitment to the security of Israel is rock solid," Obama said. "The United States will always have Israel's back."

But analysts said the Israeli leader appeared unconvinced.

"Obama went out of his way to try and send that message," political scientist Jonathan Rynhold told AFP. "But I think actually that he didn't convince the prime minister at all."

"The disagreement that was there, is still there."

Much of the West believes Iran's nuclear programme has a military aim, a charge which Tehran denies, but Israeli and US leaders are at odds over how soon the threat could become reality.

The Obama administration maintains that tough sanctions on Iran and diplomatic efforts need to be given more time before any resort to bombing raids.

Israel, however, believes that time is running out for a pre-emptive strike, and that Iran may be on the cusp of "break out" capacity -- the moment when it could quickly produce weapons-grade uranium.

Despite Obama's very public reassurances, Netanyahu appears as determined as ever to keep Iran at the forefront of public consciousness.

On Wednesday, he returned home and two days later ordered a fatal air strike against a Gaza militant leader which stirred up a hornets' nest and brought a hail of rockets slamming into southern Israel, most of them fired by the radical Islamic Jihad movement.

While the military prepared the plans, it was Netanyahu himself who gave the green light for the hit. "That decision was taken at the highest level," an Israeli official told AFP.

Media commentators said Netanyahu and his advisors can have had no doubts about the violent consequences of that killing.

"When the Israel Defence Forces decided on Friday afternoon to assassinate the leader of the Popular Resistance Committees in the Gaza Strip, it knew what it was getting itself into," the Jerusalem Post wrote, referring to the resulting barrage of rockets which landed in Israel.

But Netanyahu has used the cross-border fighting to make another point.

"Islamic Jihad, which has fired off the majority of the scores of rockets that have hit the south in recent days, is fully supported and armed by Tehran," Netanyahu told MPs from his rightwing Likud party on Sunday, in remarks reported by the media.

"Islamic Jihad is a wholly owned Iranian subsidiary, so not only did the violence in the south not push Iran off the agenda, it instead thrust Iran front and centre," he said.

Later that day, on a visit to some of the southern towns and cities coming under steady rocket fire from Gaza, Netanyahu said that Gaza and Tehran were two sides of the same coin.

"The solution to the missile threat from Gaza will only come when when the threat from Iran is resolved," public radio quoted him as saying.

Rynhold, however, did not believe that provoking the Gaza militants was done deliberately to focus minds on the Iranian missile threat.

"I think the prime minister wants to make a connection between the two and there is one," he said.

"He's using it, but I don't think it was some sort of grand plan."