North Korean leader Kim Jong Un is marking his birthday on Sunday without much fanfare. No official celebrations are planned because the date is not a national holiday.

Kim is believed to have turned 39.

The birthdays of his grandfather, Kim Il Sung, and father, Kim Jong Il, are both national holidays.

North Korean state television recently showed photographs of Kim with his daughter. In the background, there were more than 20 warheads for the Hwasong-12 mid-range ballistic missile.

Observers say Kim intends to further develop the country's nuclear and missile programs.

During a speech in late December, he stressed the need for more nuclear warheads and the development of new intercontinental ballistic missiles.