A decision to lift the suspension of Russia's anti-doping agency (Rusada) has been labelled "the greatest treachery" of clean athletes and has sent a shockwave around the Sporting World.
The World Anti-Doping Agency (WADA) has ended a three-year suspension which followed a major doping scandal.
Leading athletes and anti-doping bodies had opposed the move.
A lawyer for Russian whistleblower Grigory Rodchenkov called it "the greatest treachery against clean athletes in Olympic history."
"The United States is wasting its money by continuing to fund WADA, which is obviously impotent to address Russia's state-sponsored doping," said Jim Walden.
WADA president Sir Craig Reedie said the reinstatement was "subject to strict conditions".
"This decision provides a clear timeline by which WADA must be given access to the former Moscow laboratory data and samples," the 77-year-old Briton said.
He said the "great majority" of the 12-strong executive committee had voted in favor of the recommendation at a meeting in the Seychelles.
How the scandal unfolded
December 2014: As many as 99% of Russian athletes are guilty of doping, a German TV documentary alleges.
November 2015: A Wada commission publishes an independent report alleging widespread corruption, amounting to state-sponsored doping in Russian track and field athletics. Rusada is declared non-compliant.
May 2016: Former Moscow anti-doping laboratory boss Grigory Rodchenkov, who has turned whistleblower, says dozens of Russian athletes at the 2014 Winter Olympics in Sochi had cheated.
July 2016: Russia operated a state-sponsored doping programme for four years across the "vast majority" of summer and winter Olympic sports, says a report from Professor Richard McLaren.
August 2016: International Olympic Committee (IOC) decides against imposing a blanket ban on Russian athletes at the 2016 Olympics in Rio. Individual sporting federations rule instead, with 271 Russians competing.
December 2016: Wada publishes the second part of the McLaren report which says more than 1,000 Russian athletes benefited from doping.
January 2017: Rusada and Russian sport authorities given list of criteria to achieve before winning back recognition.
March 2017: Wada says Russia's anti-doping reforms are not happening quickly enough.
February 2018: Russia are banned from competing at 2018 Winter Olympics in South Korea by the IOC, but 169 athletes who prove they are clean allowed to compete under a neutral flag.
May 2018: Wada writes to Rusada offering 'compromise' solution.
September 2018: News of the compromise, revealed by the BBC, prompts fury from athletes and doping bodies.