South Korea's unexpected, unelected new leader

South Korea's Prime Minister Hwang Kyo-ahn makes an announcement at the government complex in Seoul on November 3, 2015. (Photo: AFP/Jung Yeon-Je)

It's a role that Hwang can never have imagined for himself when he was appointed prime minister by President Park Geun-hye in May last year.

In a country where nearly all political power lies in the hands of the executive, the prime minister is a largely ceremonial figure who, more often than not, is the first head to roll in the event of a political crisis.

In Hwang's case, however, the tables were turned and it was his boss who got the push after lawmakers voted to impeach Park over a snowballing corruption scandal.

The move stripped Park of her substantial powers and transferred them to Hwang, making him acting president of Asia's fourth largest economy until such time as the Constitutional Court rules on the validity of Park's ouster - a process that could take up to six months.

DAUNTING TASK

It's a daunting task for the 59-year-old, with the country still reeling from the political crisis that led to Park's impeachment, and troubles-a-plenty on the economic and national security front.

South Korea is suffering from an extended slowdown in economic growth and feels increasingly menaced by North Korea's push for nuclear statehood - two issues affected by the ongoing presidential transition in key ally the United States.

In an effort to reassure the country, Hwang made a televised address shortly after Park's impeachment, pledging to keep a firm hand on the economic tiller and protect against any provocation by Pyongyang.

"At such a critical time ... I will make the utmost efforts to fulfil my obligations as acting president and to maintain stability," Hwang said. "More than anything else, I will maintain solid national security," he said, with a particular reference to the North Korean nuclear threat.

With just over a month to go to the inauguration of US president-elect Donald Trump, he vowed to cement ties with the new administration of a country that maintains a permanent military presence of nearly 30,000 troops in South Korea.

"Dear South Koreans, the whole world is watching us ... please rally your support to overcome the challenges we face at home and abroad," he added.

STERN PERSONA

Hwang's unsmiling, stern public persona has never made him a particularly popular public figure.

As a prosecutor he specialised in enforcing the South's national security laws, with a special focus on those suspected of being North Korean sympathisers.

His activities, which continued when Park appointed him justice minister, made him a target of criticism among rights activists and opposition parties.

He was so unpopular among liberal lawmakers that many had questioned whether impeaching Park was a good idea given that Hwang would take on the mantle of state power.

But Choo Mi-ae, the leader of the main opposition Democratic Party and previously a vocal critic of Hwang, said on Friday that Hwang deserved time to prove himself.

"It is important for us to minimise political chaos at a time like this," Choo said. "I hope that Hwang will be able to properly read the public mood, including the longing for reform," she added.