A decision about banning Russian athletes from the 2022 Winter Paralympics will be made on Wednesday after it was confirmed the full Ukraine squad will take part in Beijing.
All Russian athletes have arrived before the Games start later this week.
"Any decision we take is open to legal challenge from different sides," said International Paralympic Committee president Andrew Parsons.
"This is what we need to be very careful about because it could be from Russia or from other nations.
"We need to make a decision based on our constitution and the values we stand for."
Russian athletes will compete under the Russian Paralympic Committee flag at the Winter Paralympics following a ban imposed in 2020 for state-sponsored doping.
At Pyeongchang in 2018, they competed under a neutral flag for the same reason.
Parsons said the IPC understood some athletes from other nations might choose not to participate if the Russians are allowed to take part.
Ukrainian athletes - as well as the British Olympic Association- have called for Russians to be excluded from the event.
In a wide-ranging interview with BBC sport editor Dan Roan, Parsons also said:
- The events in Ukraine were "horrifying and should not be happening in the 21st Century".
- The Sochi 2014 Paralympics did not legitimise Russian President Vladimir Putin's regime.
- Friday's opening ceremony will be used to promote "a message of peace".
- Athletes are allowed to protest if "it comes from a positive angle", although "rules are in place" for the podium and ceremonies.
The full Ukraine team, which consists of 20 athletes and nine guides across biathlon and cross-country skiing, will be able to compete in the Chinese capital.
There had been concerns the athletes would not be able to travel safely.
But the Ukrainian Disabled Sport