I tend to believe him over IRI. Although Netanyahu does lie, and a lot, I think the biggest lier in this whole mess is IRI. And the reason is: the supreme leader went on TV a few weeks ago and said: no one in IRI is imprisoned for their belief or not agreeing with the mullahs, aghazadehs, and their enforces. A cluster f**k of lies. He said there are no political prisoners in IRI, echoed by Zarif the Pinocchio. IRI keeps saying we have this weapon, that radar, this missile, that air defense system, etc and yet everyday Israel takes down another IRGC related terror group in Syria and Lebanon.
The thing is in the end it does not matter whether he is lying or telling the truth: the seeds of doubt about IRI's commitment to nuclear deal has been planted, paving the way for more sanctions, freer hand for Israel to punish IRI in Syria and Lebanon.
There is huge support in the US, across political spectrum, to punish IRI, even as far as disintegration of the country. Sad but true...