There was a treaty in place that was working
For sufficiently gracious definitions of "working". Iran was quite busy building up conventional weapons including delivery systems that could be re-purposed for nukes as well as moving towards nuclear weapons. There is no civilian use for 60% enriched uranium. Moreover, the number "60%" is misleading. The work to enrich isn't linear. When you have 60%, you're not 60% of the way from raw to weapons-grade, you're 95% of the way.
To put into context just how insane any claim that they had 60% for any peaceful purposes is: Most nuclear reactors use uranium enriched to 3% to 5%. 60% isn't "a bit more than usual". It's a fuckton more than any non-weapons use can reasonably explain.
And now we're in a situation where Iran has every good reason to get nukes, to defend themselves.
Iran didn't need a reason. We all know the reason they already had: Wiping out Israel.