"Just two months shy of the Olympic Games, the agency charged with monitoring Olympic athletes has chosen to devote its energies instead to 14-year-old charges against an athlete who is not involved in the coming games and who has never tested positive for the use of performance-enhancing drugs," his attorney Robert Luskin wrote.
The USADA sent Armstrong a letter dated June 12 advising of its intent to send formal charges to a review board. Armstrong and his lawyers had until Friday to submit his formal response.
The USADA letter was not publicly released but reported by the Washington Post. Armstrong made his formal response public on Friday by tweeting a link to a copy of the filing.
Lawyers for Armstrong asked the agency's review board to recommend to the USADA to end its pursuit of the allegations, which had the immediate effect of banning him competing in triathlons and, if upheld, could strip him of his Tour de France titles.
Accusations of doping have dogged Armstrong since he ascended to the top of the cycling world after overcoming cancer, but he has steadfastly denied taking banned drugs.
In February, the US Justice Department dropped an investigation centered on whether Armstrong and his teammates cheated the sponsor of their bike racing team with a secret doping program.
That decision meant he would not face criminal charges from the two-year-long probe.
However, the USADA said the end of the Justice Department's criminal probe did not mean the doping agency would halt its own course of action.
The USADA says it collected blood samples from Armstrong in 2009 and 2010 that were "fully consistent with blood manipulation including EPO use and/or blood transfusions," the Washington Post said.
EPO is erythropoietin, a naturally occurring protein, and its use is one recent way athletes have tried to artificially boost their red blood cell count and athletic performance.
In addition, the USADA alleges Armstrong, three doctors, a trainer and a team manager participated in a doping conspiracy from 1998 to 2007, saying at least 10 cyclists were witnesses.
The Texas-born cyclist won seven straight Tours ending in 2005, and after retiring he went back to race in 2009, when he finished third. In 2010 he finished way back in the pack and since retiring again he has taken up competing in triathlons.
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