Giving voice to growing frustration with US President Barack Obama and the international community’s failure to stop Iran’s nuclear march, Prime Minister Binyamin Netanyahu called on Sunday for the world to set down a clear “red line” so Tehran feels its determination.

Netanyahu, speaking at the beginning of the weekly cabinet meeting, articulated publicly what he has been saying for weeks behind closed doors: It is not enough for there to be open-ended diplomacy with Iran, and clear benchmarks need to be set so the Iranians understand there will be direct consequences for their actions.

“I believe that the truth must be told,” Netanyahu continued.

“The international community is not setting a clear red line, and Iran does not see international determination to stop its nuclear program.”

Until the Iranians see this, he said, they will not stop moving their nuclear program forward.

“Iran cannot get a nuclear weapon,” he declared.

While Netanyahu has spoken a great deal about the need for red lines in private, he has been more hesitant about doing so in public, and his comments at the cabinet meeting – according to one diplomatic official – marked a stepping up of his rhetoric.

Nevertheless, Netanyahu has still not stated clearly what these red lines should be, or what the consequences should be if they were crossed.

One of the reasons given as to why Netanyahu decided to publicly ratchet up the rhetoric was a remark by Gen. Martin Dempsey, the chairman of the US Joint Chiefs of Staff, that an Israeli attack could only delay Iran’s nuclear program, and he did not “want to be complicit” in an Israeli military action.

Government officials responded to that by characterizing it as “strange” and not in step with comments coming from the White House about unprecedented security and intelligence coordination between the two countries.

US Ambassador Dan Shapiro, in an interview with Channel 2, denied that there was any crisis between Netanyahu and Obama over the Iranian issue.

“There is definitely a narrative in the media right now – I’d say an overheated one – about tension between the US and Israel over Iran,” he said.

Shapiro added that this narrative does not “reflect the very close coordination and very intense work we’ve done together to address an issue that we perceive the same way, which is the importance of preventing Iran from acquiring nuclear weapons.”

Asked why the US did not give the Iranians a clear ultimatum – stop the nuclear program “or else” – Shapiro replied that “I think there is no mistaking what the US is prepared to do.”

Shapiro said that Obama and Netanyahu as well as their “teams,” speak regularly, and that the relationship “at the top” is “just what it needs to be.” The US envoy denied a Yediot Aharonot report Friday of a heated exchange with Netanyahu over the Iranian issue where “sparks flew” during a recent meeting with visiting US Congressman Mike Rogers (R-Michigan).

“That is a very silly story,” Shapiro said. “The published account of that meeting did not reflect what actually occurred at the meeting. The conversations were entirely friendly and professional, they always are. I always speak respectfully with the prime minister, just as the prime minister always speaks respectfully with me.”

Netanyahu’s comments at the cabinet were motivated, one government official said, by his belief that the Iranians do not believe that the international community is either serious, or determined, and that they can continue to proceed with their nuclear program unabated.

Asked whether Obama has not stated repeatedly that the US will prevent Iran from getting the bomb, the source said this has not been enough.

“Everything that has been said, and done, has not caused the Iranians to stop their nuclear program – that is the bottom line,” the official said, reflecting Netanyahu’s position.

“It is clear that all efforts have failed.”

The official said Netanyahu believes the West has not placed the Iranians on the horns of an either/or dilemma: That they either stop their development by a particular point, or face certain military action.

“They think that they can continue doing what they are doing, and it will be OK,” the official said. Netanyahu’s comment about red lines comes amid reports that he is interested in securing a pledge of US military action from Obama if Iran does not halt its nuclear pursuit.

The official said that Netanyahu’s stepped up rhetoric on Sunday was a reaction to last week’s Non-Aligned Movement summit – where representatives of 120 countries convened in Tehran, rendering hollow the claim that diplomacy was isolating Iran – and an International Atomic Energy Agency report on Iran’s nuclear program.

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According to that report, Iran had more than twice the number of centrifuges in its fortified installation at Fordow than it had in May, an indication it was moving steadily ahead.

Referring to the NAM conference, Netanyahu said that the representatives of 120 countries listened to the anti-Semitic rants of the Iranian leadership and “nobody stood up, nobody left the hall.”

This lack of protest was even worse in light of the recent IAEA report that “confirms what we have been saying for a long time – while the international sanctions are making things difficult for the Iranian economy, they are not delaying the progress of the Iranian nuclear project.”

In the prime minister’s own Likud party, MK Tzipi Hotovely circulated a petition on Sunday supporting any decision Netanyahu makes on Iran. The petition, which effectively backs a strike on Iran, was intended to counter efforts by cultural figures and security figures against an attack.

Gil Hoffman contributed to this report.