When Russian President Vladimir Putin walked side by side with his Chinese counterpart Xi Jinping on Wednesday, an open microphone caught them discussing organ transplants and the possibility that people might be able to live up to 150 years.

According to Reuters, the moment came as Putin and Xi walked with Kim Jong Un at the head of a delegation of more than two dozen foreign leaders to attend the military parade in Beijing marking the 80th anniversary of the end of World War II.

The moment was broadcast live by state television CCTV to other media outlets, including China’s state broadcaster CGTN, AP, and Reuters. China’s broadcasting and television administration reported that CCTV’s coverage of the event had 1.9 billion online views and more than 400 million on television.

As Putin and Xi walked toward the Tiananmen rostrum, where they watched the parade together with Kim, Putin’s translator was heard saying in Chinese: “Biotechnology is constantly evolving.”

The translator added, after an unintelligible fragment: “Human organs can be transplanted continuously. The longer you live, the younger you become, and you can even achieve immortality.”

In response, Xi, who was off camera, was heard replying in Chinese: “Some predict that in this century people may live up to 150 years.”

Kim smiled and looked toward Putin and Xi, but it was unclear whether the conversation was being translated for him. Putin did not appear to be speaking clearly in Russian in the CCTV video, Reuters noted.

When Xi began to speak, the video showed a wide shot of Tiananmen Square and the audio faded.

A little more than 30 seconds later, Xi, Putin, and Kim reappeared on camera as they climbed the steps toward the viewing platform for the parade.