On JCPOA, many of the critical provisions had pending expiration dates by this time [0] [1] and re-negotiation needed to happen again anyways.

Obama kicked the can down the road and Trump/Biden needed to provide the next kick.

[0] - Jan 2026, the limits on the types of centrifuges expire. Jan 2031, quantitative nuclear limits expire (enrichment ceiling).

[1] - https://www.armscontrol.org/act/2017-10/news/iran-nuclear-de...