Long rumored to be preoccupied with their health and longevity, two of the world’s most powerful autocrats, Chinese President Xi Jinping and Russian President Vladimir Putin, were caught in a hot mic moment Wednesday ahead of a military parade in Beijing as they spoke of organ transplants and achieving immortality.

The remarks, intended to be private but captured on a livestream of the event, came as Putin and Xi, both 72 years old, climbed the stairs to a platform overlooking Tiananmen Square in the heart of the Chinese capital to watch the parade.

“As biotechnology develops, people can keep replacing their organs through transplantation and keep getting younger, even achieve immortality,” Putin, whose words were translated into Chinese via an interpreter, told Xi. Putin’s original remarks could not be heard clearly.