At the beginning of her press conference late on Monday evening, US Secretary of State Hillary Clinton, referring to Iran, said something many might have found rather innocuous.“We will use all elements of American power to prevent Iran from obtaining a nuclear weapon,” she said, after saying that everyone prefers a diplomatic resolution to the crisis.One might be forgiven for thinking that this is something US leaders, from US President Barack Obama on down, have been saying over and over for the last three-and-a-half years.But one would be mistaken. This language, part of a written statement Clinton read before taking a few questions, was the US ratcheting up just a notch, or even just a quarter of a notch, its rhetoric on Iran.And that is not insignificant.One element of the tactics Washington and the international community use regarding Iran that irks many in Jerusalem is that Tehran has never really been faced with a clear ultimatum that says either they stop spinning centrifuges and ice their nuclear weaponization process, or wave after wave of fighter jets with bunker-busting bombs will be on their way. Either halt the nuclear process, or face US “shock and awe.”Instead, what the Iranians – and everyone else – have been hearing has been very general statements about not taking options off the table; about the US deeming it unacceptable and not in America’s interests for Iran to have nuclear weapons; of a rejection of a policy of nuclear containment vis-à-vis Iran; and of the American president saying he has “Israel’s back.”The US also said it was unacceptable for North Korea to get nuclear weapons, yet Pyongyang tested a device. Washington was opposed – and stated its opposition to a nuclear Pakistan – but that didn’t deter them, either.While all the general statements about Iran are swell, they did not do the job. Tehran has not stopped its nuclear program, and there are many sitting in positions of power in Israel who feel they have not halted the program because they have not yet really felt the “or else” part of the “stop or else” equation.Up until now, Obama has never said, “I will prevent Iran from getting nuclear weapons, even if it takes calling in the troops. Period.” Not a vacillating “my objective is” or “US policy is,” but rather “I will not allow Tehran to go nuclear.”There may be very good reasons for not doing this, from not wanting to tie his hands to a concern that if Tehran goes ahead with its program despite the threats, and if the US does not act, then Washington’s prestige abroad will be severely compromised.But from Israel’s perspective, if the “big stick” is not clearly seen in Iran, if the threat of an attack is not foremost in the ayatollahs’ minds, than there will be no change in policy. If they do not fear a credible military option, then they have no reason to show flexibility in negotiations.That they have not shown any flexibility so far – and Clinton said as much in her press conference – indicates that they have not yet internalized the possibility of a military option. But without that internalization, the chances of negotiations succeeding are slim.Which was what gives Clinton’s words significance. Her saying the US would use “all elements of its power” to get Iran to stop was by no means a military-backed ultimatum – this was not the rhetorical equivalent of the sinking of the Bismarck – but it was a bit more than “all options are on the table.” What will be interesting to watch now is whether this line will become the template for high-level US officials when discussing Iran, or whether it was a one-off comment made specifically in Jerusalem to try and allay Israeli concerns.Truth be told, a very similar formulation was used by Obama himself in February 2009, just a month after he took office. At Camp Lejeune, North Carolina, speaking to US Marines about his plans for ending the Iraq war, Obama said he was “developing a strategy to use all elements of American power to prevent Iran from developing a nuclear weapon.”Since that speech, however, that formulation has not been a central part of the public debate on Iran. Clinton put it back there on Monday.The significance of this needs to be seen within the greater timeline of the whole Iranian nuclear issue.Tehran has been pursuing its nuclear aims since at least 1995.Change in the world’s policies toward it has been glacially slow, not meteoric. Clinton’s comments may be a part of that glacial change.