Mack Horton finished second. His principles came first.

After claiming a silver medal in the 400-meter freestyle at the 2019 World Aquatics Championships in South Korea, Horton, an Olympic gold medalist swimmer from Australia, refused to stand on the podium beside China’s Sun Yang or acknowledge his longtime rival, whom Horton labeled a “drug cheat” prior to the 2016 Olympics. When Horton defeated Sun in Rio, he called it a “win for the good guys.”

Following this event, Horton, 23, alluded to his reason for snubbing the fellow Olympic gold medalist, and breaking with tradition.

“Frustration is probably it,” Horton said. “I think you know in what respect.”

In 2014, Sun was suspended for three months after taking a banned heart medication. In September, Sun, 24, was accused of smashing a vial of blood with a hammer after samples of his drug-tested blood had been drawn, according to multiple reports.

Sun has denied any wrongdoing, and has not faced any additional punishment from FINA, but the World Anti-Doping Agency has appealed the ruling, leading Sun to ask for the Court of Arbitration for Sport to grant him a public trial prior to the 2020 Olympic Games.

“Disrespecting me is OK, but disrespecting China was very unfortunate and I felt sorry about that,” Sun said of Horton’s actions.

The International Swimming Federation plans to issue a warning letter to Horton and Australia’s swimming federation.

“While FINA respects the principle of freedom of speech, it has to be conducted in the right context,” the federation said in a statement.