The announcement by Iran today that they have resumed 20% enrichment is problematic both technically and politically, but need not be a deal breaker. #IranDeal #JCPOA 1/x

This step is an obvious next action for Iran in response to the US withdrawal from the #JCPOA. Like the previous actions, it can be reversed relatively quickly. They will not learn much new since they had significant experience with 20% enrichment before the Iran Deal. 2/x

There would have been no defensible reason for Iran to enrich to 20% if the United States had not withdrawn the nonpro sanctions waivers. Until then, Russia was returning Iran’s own 20% enriched uranium in 5 kg increments and only when the previous material was used. #OwnGoal 3/x

I worry that this action will limit the room for action for the incoming Biden administration to try to get Iran back into compliance with the JCPOA and then start working on next steps. 4/x

This step may also finally expend the patience, and political space, of the EU/E2+UK who have been keeping the embers of optimism burning for nearly two years. 5/x

It is vital now, as ever, that Iran comply fully with the @iaeaorg verification and monitoring activities so that the world has a clear understanding of Iran’s nuclear activities. 6/x

I hope this is not the beginning of an even more dangerous period of escalating nuclear activities that ends with Iran back on the brink of a short-notice nuclear weapons capability. That is a precipice we walked back from in 2015, and we must not return to the edge. /fin