Just got a message from the Fan ID setup for the World Cup saying that it is possible for foreigners possessing a Fan ID to transit Belarus on their way to and from Russia. Don't know if this applies to road as well as rail travel.
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Dear spectators of the 2018 FIFA World Cup™!FAN ID holders entering the Russian Federation territory in the period from the 4th of June to the 15th of July and exiting the Russian Federation territory from the 4th of June to the 25th of July 2018 have the right of visa-free transit through the territory of the Republic of Belarus with FAN ID both on a laminated form and in electronic form and a valid identity document (passport) in the period from the 4th of June to the 25th of July 2018.More details on the Russian and Belarusian State borders crossing you can find on the Ministry of Foreign Affairs of the Russian Federation official website following the link:"
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