It is my considered opinion that following news from SO14 concerning "Jesus" SO17 plan to detonate a device at Westminster aided by MI5, having taken everyone to the BR tube emergency exit. Then a claim will be made that they died & a tit for tat is planned at the Kremlin or in Beijing.
This story in the Mirror, that means return as given in code presents ivy Mike as a perfect option. https://www.mirror.co.uk/news/uk-news/what-would-happen-nuclear-bomb-8514152