Russian and Belarusian runners will not be allowed to take part in this year's Boston Marathon because of the invasion of Ukraine, organizers said on April 6.
Russian and Belarusian athletes living in their respective countries are barred from the April 18 race, the Boston Athletic Association said.
However, Russian and Belarusian citizens not residing in either country would be allowed to take part, but not under the flag of either nation.
"Like so many around the world we are horrified and outraged by what we have seen and learned from the reporting in Ukraine," Boston Athletic Association chief executive Tom Grilk said.
"We believe that running is a global sport, and as such, we must do what we can to show our support to the people of Ukraine," Grilk added in a statement.
The statement did not say how many Russian or Belarusian athletes had entered this year's showpiece.
The Boston Marathon, one of the world's major marathons, is returning to its traditional April slot this year after disruption caused by the pandemic.
The race was canceled in 2020 and then held in October 2021 with a smaller-than-usual field.
In 2019, the last Boston Marathon not affected by the pandemic, 59 runners in a field of more than 30,000 were from Russia and Belarus.
Russia has been increasingly isolated by the sporting world following the country's invasion of Ukraine.
Soccer governing bodies FIFA and UEFA have suspended Russia from all international competitions, including the World Cup, while organizations such as Formula One racing have canceled events in Russia.