The World Anti-Doping Agency (WADA) is under fire this week after a pair of news outlets, including the New York Times, reported that 23 Chinese swimmers quietly tested positive for the same banned substance prior to the 2021 Tokyo Olympics.

WADA confirmed the substance of the news reports over the weekend, including the number of positive tests and the substance involved, trimetazidine. But it said it did not push for the swimmers to be punished at the time because it had accepted the findings of a Chinese investigation, which said the positive tests were caused by contamination at a hotel kitchen and the athletes were innocent.

WADA also said it did not have the power to disclose the positive tests, under current anti-doping rules, because China's anti-doping arm (CHINADA) ruled that no anti-doping violations were committed.

The scandal has sparked outrage in some corners of the anti-doping world, with U.S. Anti-Doping Agency chief Travis Tygart among those criticizing WADA and CHINADA for "(sweeping) these positives under the carpet)." It's also raised both new and old questions about the convoluted processes and guardrails of the global anti-doping system, with the next Summer Olympics in Paris now less than 100 days away.

So what's all the hubbub about exactly? Here's a breakdown of what happened, what the key players have said and why the Chinese swimming case has inflamed so many long-standing frustrations in the world of Olympic sports.

When did this scandal start?

In a virtual news conference Monday, WADA offered a detailed timeline of the events courtesy of general counsel Ross Wenzel, who worked on the case for WADA as an outside lawyer prior to assuming his current role in 2022.

According to Wenzel, Chinese anti-doping authorities collected 60 urine samples at a national swimming meet that ended January 3, 2021. More than two months later, on March 15, CHINADA informed WADA that it had recorded 28 positive tests. In April, CHINADA said it would investigate, with the help of public health authorities.

By the end of May, CHINADA relayed the preliminary findings of its investigation, which found trace amounts of the banned substance at a hotel where all 23 of the athletes were staying − specifically, in spice containers at the hotel's kitchen and drainage units in its hotel. It informed WADA on June 15 that it would not be charging the swimmers with anti-doping violations, officially ruling that the positive tests were caused by environmental/food contamination.

What is trimetazidine, or TMZ?

If this substance sounds familiar, it's because it garnered headlines in another bombshell doping scandal not too long ago. Trimetazidine, or TMZ, was the banned substance at the heart of the controversy involving Russian figure skater Kamila Valieva at the 2022 Winter Olympics in Beijing.

TMZ is used to treat angina and other heart-related conditions and has been on WADA's prohibited substances list since 2014, because it can improve endurance and blood flow.

Valieva, who has since been banned for four years, claimed she unknowingly ingested TMZ through a strawberry dessert that was given to her by her grandfather.

How did it allegedly get into the Chinese swimmers' hotel kitchen?

In its investigation, Wenzel said CHINADA did not ask each of the 23 Chinese swimmers who tested positive for TMZ, individually, about how they might have ingested it. Athletes who claim contamination as the reason for a positive drug test are generally required to identify the potential or likely source of contamination.

Wenzel said CHINADA "didn't hypothesize in their report" why trace amounts of a banned heart medication were found in the kitchen of a hotel where elite swimmers were staying during competition.

"The ultimate source, meaning how the TMZ got into the kitchen, was not discovered," Wenzel said.

So what did WADA do? What could it have done?

WADA officials said that because of a surge in COVID-19 cases in the region at the time, they were not able to travel to China to investigate. They largely relied on CHINADA's reporting of the facts, which has since raised some eyebrows given the Chinese government's careful control of the sporting infrastructure there.

WADA's science department did some digging on the circumstances of the tests, the quantities involved and the substance itself. The department's head, Olivier Rabin, said his team contacted the original manufacturer of TMZ, which shared confidential and unpublished information about the substance. WADA also considered − and later ruled out − the possibility that athletes could have been microdosing.

WADA noted that all of the positive tests were limited to athletes who, according to CHINADA, stayed in the same hotel, while athletes who stayed in a different hotel did not test positive.

"All of those athletes were in the same place at the same time when the positives arose, and all of these sample results were at consistently low levels," Wenzel said.

WADA could have challenged CHINADA's decision at the Court of Arbitration for Sport (CAS). But Wenzel said it decided in early July not to do so, because it couldn't find sufficient evidence to prove that this wasn't a case of contamination and its lawyers believed that such an appeal would almost certainly fail.

WADA accepted CHINADA's decision not to punish its athletes, considered the athletes innocent for all intents and purposes, and did not publicly acknowledge the case prior to the start of the 2021 Olympics later that month. China's 30-person swimming team went on to win six medals at the Tokyo Games, including three golds.

Why wasn't this disclosed at the time?

Here's where this all gets pretty complicated. While WADA is at the top of the anti-doping food chain, much of the actual system is facilitated by national anti-doping bodies like CHINADA or USADA. WADA essentially makes the rules and ensures they're being followed.

National anti-doping bodies are required to publicly disclose when an athlete tests positive for a banned substance, even if they determine that the anti-doping violation wasn't the athlete's fault. However, if the anti-doping body determines that no violation occurred in the first place, they don't have to say anything. And that's what happened here.

WADA officials said they couldn't have publicly disclosed anything about the case unless CHINADA did so, or they decided to take it to CAS. Neither occurred, so WADA stayed quiet for nearly two years, until news reports emerged over the weekend.

"It's a question about whether you want or not to expose the innocent athletes, right?" WADA president Witold Banka said Monday. "We have to take into account that through publishing the names of athletes without anti-doping rule violations, you expose the innocent athletes and you can damage their image. So this is a discussion which is very important, and our role is to protect innocent athletes as well."

What has USADA said?

Tygart, USADA's chief executive officer, has been a frequent critic of WADA. And he did not hold back here, describing the handling of the Chinese swimmers' cases as "crushing" and a "potential cover-up."

That statement sparked an incendiary back-and-forth with WADA over much of Saturday, in which WADA took the unusual step of releasing a statement purely to bash Tygart and USADA. Specifically, it called his statement "defamatory" and "politically motivated." Tygart then released his own statement, chalking WADA's up to "scare tactics."

"When you blow away their rhetoric, the facts remain as have been reported: WADA failed to provisionally suspend the athletes, disqualify results, and publicly disclose the positives," Tygart said Saturday afternoon. "These are egregious failures, even if you buy their story that this was contamination and a potent drug ‘magically appeared’ in a kitchen and led to 23 positive tests of elite Chinese swimmers."

How is this different from the Kamila Valieva case?

WADA stumped for Valieva to be punished in her case, and there have been questions about how its handling of the Chinese swimmers' positive tests could potentially influence Valieva's appeal − or give her grounds to claim that she was treated unfairly.

Wenzel said there were key differences in the Valieva case, however, some of which are fairly technical. In Valieva's case, for instance, Wenzel said WADA wasn't able to rule out the possibility that Valieva had knowingly ingested TMZ several days before she tested positive, and the reasoning she initially gave for the positive test wasn't supported by "the pharmacological secretion profile of TMZ."

What happens next?

In the short-term, probably nothing. None of the parties involved seem interested in relitigating the facts of the case. WADA officials spent nearly two hours Monday defending their handling of it, and Banka said: "If we had to do it over again now, we would do exactly the same thing."

This scandal figures to raise plenty of questions in the leadup to this summer's Games, which begin July 26, and could lead to some uncomfortable moments when Chinese swimmers line up to compete in Paris. There is also a slight chance that it could result in a federal investigation in the U.S. Under the Rodchenkov Act, passed in 2020, the Justice Department can pursue criminal prosecution in international doping incidents that might have impacted U.S. athletes.

Contact Tom Schad at [email protected] or on social media @Tom_Schad.