Binyamin Netanyahu, the Israeli prime minister, has said that an attack on Iran's nuclear facilities is not inevitable. But he claimed it is the threat of military action, not sanctions, that will deter Tehran from developing an atomic bomb.

Following his White House meeting with Barack Obama this week, Netanyahu differed with the president over the value of diplomacy and was sceptical about a fresh round of talks between Tehran and the major powers, telling Fox News that Iran has "bamboozled the west".

The Israeli prime minister said that, like Churchill, he is sounding the "jarring gong of danger" to wake democracies from their slumber to the coming danger. Asked if "war is inevitable", Netanyahu replied: "I don't think so".

But he brushed off Obama's demand this week for an end to the "loose talk of war" and "blustering" over Iran - criticisms evidently aimed at months of threats from within Israel - to argue that Tehran is more likely to respond to fear of attack than sanctions.

"We've seen, in fact, that Iran backed off from its nuclear programme, its nuclear weapons programme, really only once in the 15, 16 years that I've been warning the world about the dangers of a nuclear-armed Iran. And the only time they backed away was in 2003, when they thought there'd be a credible military threat against them," he said. "So in fact, the paradox is that if they actually believe that they're going to face the military option, you probably won't need the military option."

The US defence secretary, Leon Panetta, reiterated the military threat on Iran by saying that Washington has been preparing the plans for an attack "for a long time". But, in an interview with the National Journal, he marked out the sharp difference with Israel over the timing of any assault by effectively saying that if an attack becomes necessary it would be better to wait and let the US carry it out.

"If (Israel) decided to do it there's no question that it would have an impact, but I think it's also clear that if the United States did it we would have a hell of a bigger impact," he said.

At their White House meeting this week, Obama sought to persuade Netanyahu to hold off on any attack against Iran with a promise that even if Tehran was able to move its nuclear programme to fortified underground facilities beyond the reach of Israel's military, the US would still be able to destroy them.

But that requires Netanyahu to place the decision on whether to attack Iran in Washington's hands, something he has said he will not do.

The Israeli premier declined to discuss a possible timeline for Israeli military action but said the Iranians are getting "very, very close".

He said that increasingly stringent sanctions are taking their toll on Iran, but not where it matters.

"It's hurt their economy. But it has not stopped their (nuclear) programme by one wit," he said.

While Obama has said the US assessment is that Iran has not yet made the decision to develop a nuclear bomb, Netanyahu repeated his assertion that he has no doubt that is what Tehran intends to do.

"Why do you think Iran is doing all of this - developing these underground halls with thousands of centrifuges to enrich uranium? … They're building ICBM, intercontinental ballistic missiles, to carry, what? Medical isotopes? That's their explanation? They are absorbing these crippling sanctions," he said. "So I don't think anyone seriously thinks that Iran is doing all of this, going through all of this huge investment, taking huge risks for anything but a nuclear programme, and I think we should recognise that."

Netanyahu was sceptical a new round of talks agreed between Iran and the five permanent members of the UN security council plus Germany will change very much.

The group appealed in a statement on Thursday for Iran to enter into a "serious dialogue" on its nuclear programme and said it was "concerned that, despite efforts made so far, no agreement was reached, including on the access to relevant sites in Iran, requested by the [International Atomic Energy Agency]".

It called for Iran to fulfil an undertaking to grant access to the Parchin military base where IAEA inspectors suspect Tehran has possibly undertaken research into triggers for nuclear weapons. Diplomatic pressure was ratcheted up on Iran over the site with the release of satellite pictures suggesting it was cleaning up the military base to hide evidence of the research. However, the pictures were met with scepticism by some experts.

Netanyahu said Tehran has previously used negotiations to "deceive and delay" and could do so again.

"The only way you get a result if you got them to agree to freeze their enrichment, take out all the enriched uranium that they have enriched, take it out of Iran, the stuff that can make bombs. If they want to make medical isotopes, you can give them back - uranium that can serve that purpose, a peaceful purpose," he said. "And they can dismantle this underground facility they have in a place called Qom, which is basically an underground nuclear bunker. They could do all of that. Then you would have an indication that the talks have actually produced something. But personally, I'm sceptical. I think they have bamboozled the west. And they think they can get away with it."

Asked whether the intelligence on Iran might prove to be as flawed as the false reports of weapons of mass destruction in the runup to the invasion of Iraq in 2003, Netanyahu said there was "no comparison".

"In the case of Iraq, I was on the Israeli cabinet when we discussed this issue. We didn't know. We couldn't say that they didn't have a nuclear weapons programme, we couldn't say if they did. In the case of Iran there is absolutely no question. We share all of that information. We know the stockpiling of enriched uranium. We know the development of ICBMs. We know a lot more. And we share this information. I don't think that's comparable."

During his visit to Washington this week, Netanyahu persuaded leading members of Congress that Israel is serious about attacking Iran - and that the warnings of military action are not just bluster in order to pressure the west in to ratcheting up sanctions on Tehran.

They include Dianne Feinstein, the chair of the Senate intelligence committee, who told CNN that following her meeting with Netanyahu and discussions with other officials she believes Israel is serious about being prepared to attack Iran.

"I followed the intelligence very carefully, I've met with Israeli generals … with the president, and here's what I believe: I believe that Israel will attack. I believe that it is important that diplomacy be given an opportunity, I believe it is possible to achieve a diplomatic solution," she said.

Asked about Netanyahu's attitude, Feinstein said: "His resolve is very firm, no one should doubt that. He told us he's not asking anything of the United States. Israel believes they are prepared to handle it. Now what happens after an attack is very different."

But the senator said Netanyahu is likely to respond to Obama's appeal to give sanctions time to work.

"I believe the Israelis will wait to see what happens," she said.