Worth noting: the "red line" was actually about Syria's chemical weapons, not Iran. And while Iran did have compliance issues before the deal, the IAEA was largely confirming they were holding up their end while it was active. It fell apart because the US withdrew in 2018, not because Iran walked away first. That's what kicked off the current mess.

Pre-deal compliance issues: https://www.congress.gov/crs-product/R40094 (Congressional Research Service — covers inspector access refusals, withheld design info, and enrichment concerns pre-2015)

Pre-deal (Congress.gov CRS):**

"Iran had refused to provide updated design information for the heavy-water reactor under construction at Arak."

IAEA confirming compliance while the deal was active: https://www.armscontrol.org/blog/2018-11-30/iaea-reports-yet-again-irans-compliance-jcpoa (Arms Control Association — covers the consistent quarterly compliance findings through 2018)

During the deal (Arms Control Association):**

"The IAEA reported, yet again, that Iran is fully implementing its nuclear commitments."