Words matter.  Nowhere more so than in our diplomatic sparring across the globe, when they’re often all we’ve got.  An overused trope can transform an intended ultimatum into toothless farce.

Perhaps that’s why official warnings toward Iran have started to conjure for me Wallace Shawn’s Vizzini in The Princess Bride.  Anyone who came of age in 1980’s America knows the bit: To allay concerns after having kidnapped Princess Buttercup, Vizzini assures his partners in crime that their being followed would be “inconceivable”.  It quickly becomes clear of course, that the group is in fact being tracked.  And as increasingly unfathomable scenarios come to fruition, Vizzini’s continued and adamant invocation of “inconceivable” gains in comic force.  Finally, Mandy Patinkin’s Inigo Montoya is forced to point out, “You keep using that word.  I do not think it means what you think it means.”

So it goes with the ubiquitous refrain of “unacceptable” that has long peppered Iran repartee amongst the chattering class, and the incredulity with which we greet each grave new development.

Unacceptable said President Bush in 2006, in response to reports of Iran’s increased uranium enrichment.  Unacceptable said UN Ambassador Susan Rice in 2009, that Iran had plans to build additional enrichment facilities.  Unacceptable said then-Secretary of Defense Leon Panetta in 2011, in response to an IAEA report that certain Iranian activities were not applicable to objectives “other than a nuclear explosive”.  Unacceptable said the EU earlier this year, that Iran should continue to deny IAEA access to Parchin, where military testing is believed to have been underway for quite some time.  And unacceptable that Iran should acquire nuclear weapons, has said everyone from President Obama to Secretary of State Kerry to British Prime Minister David Cameron and German Chancellor Angela Merkel.

Much as we can see how we’ve aged more starkly from an old photograph than by looking in the mirror each day, so too can we see just how far we’ve drifted vis-à-vis Iran by filtering the current moment through the prism of the last decade.  From modest enrichment at its Natanz facility in 2003 that at the time was considered grievous and now seems almost quaint, we have inched our way toward a 2013 state of affairs that accommodates an Iran with 10,000 centrifuges enriching uranium to 3-5% at Natanz, 2700 centrifuges enriching uranium to 20% at its underground Fordow facility and enough amassed enriched uranium overall for five bombs, if enriched further.

While we have thrown down the “unacceptable” gauntlet at the emergence of each new development and have taken successively more crippling steps to curb Iran’s nuclear enthusiasm, the P5+1 negotiations with Iran that resume today in Kazakhstan expose what a nosedive our demands have taken over the last decade.  The offer on the table shows how, preferred verbal tic aside, Iran has in fact secured our tacit acquiescence to all but the most recent of its achievements.  For years it remained standard fare that Iran must stop any and all enrichment; the pending P5+1 proposal does away with the requirement that Iran stop enriching at the 3-5% level, asking only that they stop enriching to 20%.  The proposal dispenses with Israel’s request that Fordow be dismantled (never mind the rightful distress with which the facility’s revelation was met by the US, UK and France in 2009) asking only that Iran curtail its operation.  In other words, there’s been acceptance-a-plenty, all absent the most basic assurances from Iran.

We must of course chase down any opening that allows for a peaceful conclusion of the Iran dilemma, for the sake of all involved.  But we must know when a seeming opening is a brick wall in disguise and when we’re being courted down a gangplank we’ve walked before.  In 2003, the EU-3 comprising England, France and Germany penned an agreement with Iran in which Iran committed to more stringent inspections and to suspend uranium enrichment.  Despite the endless prevarication that followed, it took until 2006 for Iran to be referred to the UN.  The Iranians had wrangled yet three more years of free rein, taking advantage of how invested those across the table were in wanting to keep the process alive and in wanting to believe that it stood a chance.  Versions of this scenario have been playing on continuous loop ever since.

The current P5+1 talks are no different with regard to the staving off of punitive measures Iran hopes to pocket, no different with regard to the bought time Iran will try to extract.  But we can no longer afford bamboozled years of asymmetric hide-and-seek.  We can no longer afford a de-facto assent to Iran’s upping of the ante; reportedly on tap for the coming months are the installation of next generation centrifuges that would shorten Iran’s sprint distance to weaponization and scoping for additional nuclear sites.  And this just in from IAEA Director General Yukiya Amano, for any of those still wondering: there is “crosschecked” evidence that Iran has been “engaged in activities relevant to the development of nuclear explosive devices in the past and now”.

If the term “unacceptable” is so irresistible, what we should firmly attach the favored moniker to are protracted sham negotiations that threaten to ease pressure on Iran, defang the military threat of any credibility and enable Iran to blithely advance its nuclear ambitions behind a smokescreen of ersatz bonhomie.  Otherwise we’ll soon be forced to confront the last remaining and largest looming “unacceptable” of all – a nuclear Iran.  Given our track record of reneging on what we deem unacceptable, accept it we might.  Which in the words of the beloved Vizzini, would be truly inconceivable.