North Korea profile
First Chairman, National Defence Commission: Kim Jong-un
Kim Jong-un, the youngest son of previous leader Kim Jong-il, succeeded his father on the latter's death from a heart attack in December 2011.
In 2010 he had already been unveiled as Kim Jong-il's heir apparent, and was made a four-star general despite lacking any military experience.
Soon after the death of his father, North Korean state media lauded Kim Jong-un, the newly-appointed army supreme commander, as "a great person born of heaven" and anointed him the "Great Successor" of the philosophy of juche (self-reliance), signalling a continuation of the personality cult of the Kim family into a third generation.
In April 2012 he formally took over as leader of the ruling Workers Party, with the new title of First Secretary, as his late father became "Eternal General Secretary".
He also became First Chairman of the highly-important National Defence Commission, with his late father promoted to "eternal chairman". His grandfather Kim Il-sung, who died in 1994, is the country's "Eternal President".
He ousted army chief Ri Yong-ho, who had overseen his smooth succession to power, in July 2012 and took the title of "marshal" for himself, marking the full consolidation of his political and military power.Mentor executed
It is widely believed that the task of guiding and mentoring Kim Jong-un when he assumed power was entrusted to his aunt Kim Kyung-hee and her husband Chang Song-thaek.
Mr Chang had been seen as close to Kim Jong-il and was thought to enjoy considerable influence over Kim Jong-un, but in late 2013 he was found guilty of attempting to overthrow the state and was summarily executed. His spectacular fall from grace was seen by analysts as the biggest upheaval in the North Korean leadership since the death of Kim Jong-il.
Details of Kim Jong-un's early life are scant. Born in 1983 or early 1984, he is reported to have gone to school in Switzerland and later studied at Kim Il-sung University in North Korea.
After becoming leader he began to display a more informal style in public appearances, although the official media swiftly quashed any hopes that this might mean a relaxation in totalitarian controls.
There are concerns about the young leader's health, given his obesity. State media reported that he was suffering "physical discomfort" in September 2014 after he had been seen limping for several months, and he disappeared from public view for six weeks.
Under Kim Jong-un, North Korea has continued its policy of promoting the military at home while sending mixed signals to the rest of the world about its nuclear programme. The launch of a satellite in 2012, using rocket technology banned under UN ballistic missile sanctions on North Korea, boosted Kim's standing in the ruling elite while angering his neighbours, including sole ally China.
North Korea's defiant third nuclear test in February 2013 earned it another escalation of UN Security Council sanctions, approved by China. North Korea in turn stepped up its bellicose rhetoric and announced it would restart all facilities at its main Yongbyon nuclear complex, including a reactor mothballed in 2007.
This behaviour continued after the execution of Chang Song-thaek, as North Korea test-fired two medium-range Nodong ballistic missiles in March 2014. This was in violation of UN resolutions and just hours after the US, South Korea and Japan met talks. It also marked the fourth anniversary of the sinking of the South Korean warship Cheonan.
The challenges the country faces under Kim Jong-un are the same as those it had to cope with during his father's reign - a moribund economy, international isolation and widespread poverty.