South Korea's new president was sworn in on Wednesday, just a day after a landslide election victory, and immediately declared his willingness to visit Pyongyang amid high tensions with the nuclear-armed North.
Left-leaning Moon Jae-In, a former human rights lawyer, backs engagement with North Korea in the quest for peace -- in contrast to the threatening rhetoric from the Trump administration in recent weeks.
"If needed I will fly to Washington immediately," Moon said in an inauguration speech after taking the oath of office in front of lawmakers at Seoul's National Assembly building.
"I will also go to Beijing and Tokyo and even Pyongyang in the right circumstances."
Moon will have a difficult diplomatic path to tread in his approach to the North, which dreams of a missile capable of delivering a nuclear warhead to the continental United States, and has vast artillery forces trained on Seoul.
At the same time the South is embroiled in disputes with China over a US missile defence system, and former colonial occupier Japan over wartime history.
He named former journalist Lee Nak-Yon, a four-term lawmaker, as prime minister -- a largely coordinating role and appointed a new head of the National Intelligence Service, Suh Hoon, who played a key role in preparing the past two inter-Korea summits of 2000 and 2007.
Domestically, Moon begins his term facing multiple challenges, including the aftermath of the huge corruption scandal that saw his conservative predecessor Park Geun-Hye impeached and swept him to power, but leaves the country bitterly divided.
Ahead of the swearing-in, Moon met leading lawmakers of Park's Liberty Korea party -- which has repeatedly accused him of being a Pyongyang sympathiser -- to "beg" for their cooperation.
"I will be a president to all people," he said in his speech, promising to "serve even those who did not support me" and remain "at eye-level with the people".
After the low-key ceremony he was driven through the streets of the capital to the Blue House, standing in the back of his limousine and waving to supporters.
Moon took 41.1 percent of the vote in Tuesday's election, far ahead of Hong Joon-Pyo of Park's Liberty Korea party, on 24.0 percent, and centrist Ahn Cheol-Soo on 21.4 percent.
The 64-year-old is bespectacled, reserved and mild-mannered, although some critics describe him as bland, indecisive and uninspiring.
"I liked the no-frills inauguration event and his down-to-earth style," said Lee Jeong-Mi, a Seoul office worker who watched him pass by. "He really looks like a true people's president."
Since the beginning of last year the North -- which says it needs atomic weapons to defend itself against invasion -- has mounted two nuclear tests and a series of missile launches.
In recent months the Trump administration has suggested a military option is on the table, escalating fears of conflict -- although the US president changed tone last week, saying he would be "honoured" to meet the North's young ruler, Kim Jong-Un.
Moon is expected to have his first conversation with Trump in a phone call Wednesday, Yonhap news agency said, citing unnamed Seoul diplomats.
Chinese President Xi Jinping congratulated Moon on his election, saying he would be willing to work with him on a basis of "mutual understanding and mutual respect", according to China's official Xinhua news agency.
The phrasing is Beijing's diplomatic code for acceptance of its stance.
The South's biggest trading partner, China has been infuriated by the deployment of the US anti-missile system THAAD in the country, which it sees as a threat to its own military capability.
It has taken a series of moves against South Korean firms seen as economic retaliation.
At home, Moon will have to deal with slowing growth, soaring unemployment and public frustration over widening inequality in wealth and opportunities.
The stellar expansion that pulled a war-ravaged country out of poverty has slowed down in recent years as the economy matured, with the jobless rate among those aged under 30 hitting record highs.
Such frustrations fuelled anger over Park's scandal, which exposed the cosy and corrupt ties between regulators and powerful conglomerates that have endured for decades.
The family-run giants, called chaebols, dominate Asia's fourth-largest economy but have come under fire in recent years for running their global businesses like personal fiefdoms, with minimum scrutiny by investors and regulators.
Moon tapped into the concerns in his inauguration speech, saying he would create a society that offers "equal opportunity, fair process and just outcome".
After leaving office two South Korean presidents have been jailed for corruption, one is awaiting trial, and another -- Moon's own mentor -- killed himself after being questioned over graft, but the new leader promised to stay clean.
"I will take the helm empty-handed and will retire empty-handed," he said.