WADA's executive committee concluded Moscow had planted fake evidence and deleted files linked to positive doping tests in laboratory data that could have helped identify drug cheats.
"We are getting very close to the fifth anniversary of the ARD documentary," WADA President Craig Reedie told Reuters television, referring to a German television documentary which in December 2014 alleged doping was rife in Russian athletics and ed to WADA investigations.
"It has become almost never-ending and that is disappointing because they are a sport-minded country, they are hosts of sport, they compete in sport, and it has presented huge problems to sport over the last five years."
WADA's executive committee voted to reinstate Russia's Anti-Doping Agency RUSADA in September 2018, before it had fulfilled the requirements laid out in a “Roadmap to Compliance”, and was finally given access to the data stored at Moscow’s anti-doping laboratory in January.
"It is particularly irritating after having broken the deadlock and done it in an intelligent way," said Reedie.
"There are certain parts of the world which would want to sanction Russia for doing anything at any time ... there are other parts of the world which take an entirely different view," he said."We have been dealing with a sporting problem in the middle of one of the biggest political standoffs for years ... diplomats are being expelled, hacking is going on. But you cannot walk away from it, you have to try to resolve it."