On 13 September, the Belfer Center published the slides from a presentation on the evolving global threat to nuclear and radiological transports to the Transport Security Unified Stakeholders Group. It says that attacks on transports are a constant threat, and that the theft of plutonium or highly-enriched uranium (HEU) could lead to a horrifying catastrophe, and that sabotage could also provide a serious threat. It also refers to the risk from a so-called “dirty bomb” (or a radiological dispersal device or RDD). It concludes that there remains a serious remaining risk.

https://www.belfercenter.org/sites/default/files/files/publication/transport-threat-brief-2021.pdf
Any modest contributions for my time and ongoing expenses are welcomed! I have a page where you can do so, and where one-off contributions start as low as $3, at https://www.buymeacoffee.com/KoIvM842y