When Benjamin Netanyahu arrived at Donald Trump’s Mar-a-Lago club on 29 December last year, the Israeli prime minister came with an appeal – and a not so subtle inducement.

After months of restocking air defence and other missiles after June’s 12-day conflict in which the US joined in to bomb Tehran’s nuclear facilities, Israel was ready to go again, this time with more substantial objectives.

In the press conference hosted by the two leaders, Trump appeared to dutifully echo familiar talking points of Netanyahu’s. “Now I hear that Iran is trying to build up again,” Trump said. “Then we are going to have to knock them down. We’ll knock the hell out of them. But hopefully, that’s not happening.”

The Israeli leader, like others before him, had come armed with an appeal to Trump’s ego: the award of his country’s top honour, the Israel Prize, rarely given to non-Israelis, for his “tremendous contributions to Israel and the Jewish people”.

According to the Atlantic, Netanyahu had suggested a final benefit to the famously transactional president: defeating Iran would allow Israel to wean itself off its massive reliance on US military aid.

That meeting, as multiple accounts have now made clear, was one of many contacts between Netanyahu and Trump in the weeks that followed as the latter sought to lock in US participation for a comprehensive conflict against Tehran with far grander ambitions than the previous round of fighting.

A fragile and unpopular regime was ripe for toppling, shaken by internal protests – with Iranians furious at the lethal repression of those demonstrations, according to an assessment prepared by the Mossad, Israel’s secret service.

It would be a historic opportunity requiring a short campaign. An extra benefit dangled by the Israeli leader, according to some accounts, would be that Trump could take revenge for alleged Iranian plots against his life.

What is clear from what has subsequently emerged is that Netanyahu – a self-styled “expert” on Iran – and the wider Israeli military establishment were fully invested in their pitch of an easy war.

On 28 February, the first day of the war, unnamed Israeli officials briefed the Haaretz newspaper that the Iranian threat would taper off in a handful of days as Iran’s last missile launchers were eliminated.

Another article in the same paper said Israel’s military planners had stockpiled missile interceptors for a war they assumed would last three weeks at most.

When viewed as a discrete conflict, it is as much owned by the US as Israel, but it is part of Israel’s war; the latest front in Netanyahu’s state of permanent conflict that has raged since Hamas’s attack on Israel on 7 October 2023.

That attack altered the country’s strategic calculations. And in the expanding regional conflicts that have followed in Gaza, Lebanon and now Iran, with the Houthis in Yemen and in the Syrian hinterland, a common theme has emerged: Netanyahu has promised and declared victories of which the realities are always more ephemeral and hubristic.

In Gaza, despite a horrific campaign of death and destruction, a diminished Hamas still persists among the ruins. In Lebanon, where Hezbollah was declared defeated, the organisation retains its capacity to fire rockets across the border, with Israel plunging once again into the same policy of occupying southern Lebanon that failed once before – and led to the emergence of Hezbollah in the first place.

In Iran, despite the killing of the supreme leader Ali Khamenei and other senior officials, a “decapitation” strategy has not led to Netanyahu’s promises of quick regime change but, for now at least, apparent consolidation of the regime around the Islamic Revolutionary Guards Corps.

Even if the precise dynamic of influence and persuasion remains murky, it is clear that even among senior Trump administration officials, the perception exists that Netanyahu overpromised, not least amid challenged accounts of a testy conversation between the vice-president, JD Vance, and Netanyahu to that effect.

Axios, quoting a US source using Netanyahu’s nickname, reported last week: “Before the war, Bibi really sold it to the president as being easy, as regime change being a lot likelier than it was. And the VP was clear-eyed about some of those statements.”

Others are more cautious. Trump, wrote Daniel C Kurtzer, a former US ambassador to Israel, and Aaron David Miller in a post for the Carnegie Endowment for Peace, was “a willing and full partner”.

“He was risk-ready and caught up in a self-generated aura of military power and invincibility after taking President Nicolás Maduro from Venezuela.” They concede that “Netanyahu may have determined the timing of conflict”, but Trump was “likely already on his way to war”.

As the war enters its second month, with no end in sight and with the global economy reeling from the closure of the strait of Hormuz, the detrimental consequences of Netanyahu’s promise of an “easy” war are spreading far beyond the immediate region.

In that respect, the perception of Netanyahu’s role – following his years-long advocacy for the conflict – matters as much as Trump’s own willing involvement.

As the security experts Richard K Betts and Stephen Biddle wrote in Foreign Affairs last week: “In just its first weeks, the war has cost many billions of dollars in direct expenditure, reduced support for Ukraine, put dangerous strains on inventories of the most advanced US weapons, and shocked the global economy.”

The conflict has also undermined Nato while potentially emboldening China, Russia and North Korea. And while Netanyahu has boasted in biblical terms of hitting Iran with ‘‘10 plagues”, it has not been lost on some that the Iranian and Hezbollah missiles still landing on Israel mean Passover will be spent with one eye on the bomb shelter.

For Netanyahu and Israel, there are likely to be longer term consequences in terms of diplomacy and public opinion, which – alongside the Iran question – have long obsessed Israel’s prime minister.

Already viewed with caution, if not outright distrust, in many foreign capitals, Netanyahu and his war threaten Israel’s detente with the Gulf states in the shape of the Trump-mediated Abraham accords.

“Some Arab states may blame Israel for being thrust into a war they didn’t choose,” said Raphael Cohen, the director of the strategy and doctrine programme at the Rand thinktank. He suggested that while the geopolitical landscape of the Middle East may change as promised by Trump and Netanyahu, “at least insofar as which countries are on Israel’s side – [that] may look very different once the dust settles”.

Outside the Gulf, the French president, Emmanuel Macron, last week reflected a more widespread view that US and Israeli strikes on Iran would not provide a durable solution to Tehran’s nuclear programme.

“A targeted military action, even for a few weeks, will not allow us to resolve the nuclear issue in the long term,” Macron said in South Korea as he described a military operation to open the strait of Hormuz as “unrealistic”. “If there is no framework for diplomatic and technical negotiations, the situation can deteriorate again in a few months or a few years,” he added.

More difficult to immediately quantify is the impact that fast-declining support for Israel may have on domestic politics around the globe, a phenomenon already apparent in the widespread opposition to the scorched-earth tactics of Israel’s right-far right government in Gaza and now Lebanon.

In the US, polls show that support for Israel has declined across the political spectrum, most obviously among Democrats and young voters. A Gallup survey released the day before the US-Israeli attack on Iran showed Americans are more sympathetic to Palestinians than Israelis for the first time since Gallup began measuring that question in 2001.

Since then, the downward trend has only continued, even among US Jewish voters. A survey commissioned for J Street found 60% of Jewish voters opposed the military action against Iran and 58% believed it weakened the US. A third said they believed the war would weaken Israel’s security.

Rahm Emanuel, Barack Obama’s chief of staff from 2009-10 and a former US ambassador to Japan, told Semafor that in the future it may mean the end of Israel being a unique beneficiary of US military assistance.

“They’ll get the same restrictions like any other country that buys any of our weapons. There’ll be a country among countries … It’s a different game now, and you will not get the United States taxpayers to foot the bill for you.”