The USA (and EU) downplayed the nuclear threat from Iran, because its neighbors were concerned and said that they too would pursue their own nuclear weapons. This isn't a secret. You know it too. You want "evidence" of sentiment in the Arab world and their concerns? Here's a nice summary with references to the speeches made by Arab leaders. https://www.nti.org/analysis/articles/arab-response-irans-nuclear-program/. It speaks to the arrogance of westerners that they ignored the cautions offered by the Arab leaders. Saudi Foreign Minister Saud al-Faisal criticized Iran's uranium enrichment program during a speech in Washington D.C. highlighting the possibility that the enriched uranium fuel could be used for nuclear weapons. He asked, "Where is Iran going to use these weapons? If their intention is to bomb Israel, they will kill Palestinians, Syrians, Jordanians, and Saudis, as well. "Saudi Ambassador Decries Iran Nuke Program," Associated Press, 8 February 2006. He was right 20 years ago, and is still accurate in that assessment today.
