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.

“There are estimates that humans can live up to 150 years old during this century,” Xi responded.

North Korean leader Kim Jong Un, who was walking alongside Xi and Putin, appeared to listen carefully to the exchange with great interest.

The hot mic moment was captured live by broadcasters worldwide. Part of the exchange was also broadcast by China’s state-run CGTN television network, though Xi’s response was overshadowed by the anchor’s voice.

Putin is reportedly fascinated with genetics, with media reports saying that he has given friends and family key posts in the billion dollar industry. In particular, his government has embarked on what some say is a quixotic quest for anti-aging technology, according to the reports.

Putin, himself, has been the subject of much speculation at various times that he is in ill health, though many in Western intelligence circles say these claims are unsubstantiated and often based on disinformation intended to chip away at the Russian leader’s tough-guy image.

Xi, meanwhile, has effectively positioned himself to remain as China’s leader for life, disposing of his enemies while in the process diluting the pool of a potential successor.

An heir to one of the republic’s founding fathers, he came to power in late 2012 and would have concluded his tenure as party chief in 2022 and as president in 2023. A 2018 revision to the country’s Constitution abolished term limits for the presidency, allowing him to continue the role after two consecutive terms.

Staff writer Jesse Johnson contributed to this report