Russians and Belarusians had initially been banned from competing internationally following Russia's invasion of Ukraine last year, for which Belarus has been used as a staging ground.
In March, however, the IOC issued a first set of recommendations for international sports federations to allow Russian and Belarusian competitors to return and they have since done so in most events.
Out of 4,600 athletes globally who have qualified for the July 26th-August 11th Games so far, eight are Russians and three hold Belarusian passports.
Long before Russia's invasion of the Ukraine, which Moscow calls a "special military operation", the country was already a sporting outcast for having implemented a state-sponsored doping programme that resulted in bans from competitions, including the Olympics.
The Russian Anti-Doping Agency (RUSADA) remains non-compliant, raising new concerns about the testing of Russian athletes ahead of the Paris Games.
Despite challenging conditions, the World Anti-Doping Agency (WADA) said more than 10,500 samples from Russian athletes had been collected this year, most of those in out-of-competition tests, including from athletes training in so-called ‘closed cities’.
"Despite this and given the history, WADA remains sceptical and wary when it comes to Russia," said WADA in a statement.
"We must remain vigilant and ensure that no stone is left unturned when it comes to ensuring that all the proper testing has taken place in advance of Paris.
"We encourage Anti-Doping Organisations to implement a biological passport for all athletes from Russia that may potentially compete in Paris as neutrals."
With no accredited laboratory in Russia, samples - both blood and urine - are transported with a strict chain of custody to WADA-approved laboratories outside the country.
Any Russian athlete competing must provide proof of testing through a biological passport.
United States Olympic Paralympic Committee (USOPC) chair Gene Sykes said he had discussed the situation with both WADA and the International Testing Agency (ITA) and expressed cautious confidence that American athletes would compete on level playing fields against Russian participants.
"WADA and the International Testing Authority were both at the Olympic Summit and spoke very directly about exactly what they know about testing of all Russian athletes," Sykes told reporters following a USOPC board meeting on Thursday. "That report was very thorough.
"An athlete biological passport is a concept that is well understood and requires more work, more evidence.
"In order to get to that point, once the athletes are identified, then there needs to be a lot of work done to make the entire system confident that the athletes are fully compliant."
