North Korean dictator Kim Jong Un believed to have turned 40

Exactly why the date, suggested to be 8 January, remains a secret is not known. It has been hinted at previously, with North Korean officials thanking then US President Donald Trump for his birthday wishes back in January 2020 - although they did not specify which day. Further evidence of the date had emerged six years earlier, when US basketball player Dennis Rodman sang happy birthday to Kim Jong Un in front of a crowd of thousands.