Who to believe, the US or Iran, over the negotiations?

Ever since the negotiations between the US and Iran began, whether directly or through intermediaries (Pakistan, Qatar), we have seen conflicting reports of what has or has not been achieved. The US makes big claims, and Iran denies them. Vice President JD Vance claimed yesterday that the Tehran negotiators had agreed to allow international nuclear inspectors into Iran to monitor all suspected nuke programmes. Iran said this wasn't true. Who are we to believe? It's actually the same old story. The Iranian negotiators might say something privately to someone, whether to Vance or to the Pakistan prime minister, but then in public says the opposite. What matters as far the rest of us is concerned is the public statement because that is how Iran works. The public statements are the ones that matter. So even when Donald Trump claims the Iranians have said privately that they will do this or do that, it only counts when a formal statement is made in public, and that more often than not contradicts what some Iranian negotiator might have whispered into someone's ear during negotiations. The US behave in a different way. When Trump makes bold claims about what Iran has agreed to do during private discussions, they turn out to be "in your dreams" remarks. So, for example, Trump said Iran had agreed to hand over the 440 kilograms of highly-enriched uranium and that the US and Iran would work together to dig out the material in canisters from deep underground where they were buried by the B-2 bombing in June last year. Tehran said they never agreed to that. So, this is what we have to put up with for the next 60 days or, claims from both sides which clash. The lesson is to listen to what Iran says publicly because that is when the supreme leader and his military backers have agreed what to make public. All the supposed private stuff doesn't really matter.