The International Fencing Federation (FIE) on Friday decided to allow Russian and Belarusian athletes to compete in Olympic qualifying events, sparking outrage in Ukraine.
Fencing became the first Olympic sport to reopen events to fencers from the two nations, one year after their exclusion due to the war in Ukraine.
After the decision at an extraordinary congress in Lausanne, Ukraine's fencing body was in "shock" while their Russian counterparts expressed "gratitude".
Fencing's qualifying process for the 2024 Paris Olympics is due to begin in April.
FIE's decision will take effect from April "subject to possible recommendations or future decisions of the International Olympic Committee (IOC)," a delegate told AFP.
Athletes could qualify and still be barred by the IOC from the Games.
Around 65 percent of FIE voted for the return to competition of Russian and Belarusian athletes, teams and officials, the delegate who did not wish to be named told AFP.
"We are deeply shocked and outraged by this decision and we immediately convene a meeting of the Presidium to decide our response to the decision of the FIE and its possible appeal," the Ukrainian Fencing Federation said in a statement.
Their Russian counterparts welcomed the decision.
"The first step has been taken. I am grateful to colleagues from foreign federations," Ilgar Mamedov, president of the Russian Fencing Federation, was quoted as saying by the Ria Novosti news agency.
He said he was worried that there would not be time for "reintegration" by mid-April.
The Ukrainian delegation had sought to have the vote removed from the congress agenda but the request was turned down by the 136 voters.
In January, the IOC said it was seeking a "pathway" for Russians to take part in the Games.
Following that announcement, the Olympic Council of Asia (OCA) offered athletes from both countries the chance to compete in this year's Asian Games.
That was a significant move because they could gain qualifying marks in competition in Asia to allow them to compete in Paris.
Africa's National Olympic Committees voted on March 4 in favour of Russian and Belarusian athletes to compete at the 2024 Paris Olympics.
Russian fencers won three gold medals at the Tokyo Olympics, while competing under the banner of the Russian Olympic Committee.
Russia has long had a leading role in FIE. It was run for 14 years by the Russian oligarch Alisher Ousmanov who was blacklisted by the European Union after the invasion of Ukraine and passed interim control to Emmanuel Katsiadakis, a Greek.