US President Donald Trump has landed in Hanoi, Vietnam for two days of talks to try to persuade North Korean leader Kim Jong Un to give up his nuclear arsenal.
Mr Trump arrived on Air Force One after flying half way around the world from Washington DC, while Mr Kim arrived earlier, following a two-and-a-half-day train journey from Pyongyang.
They are due to have dinner tomorrow and continue talks on Thursday.
Mr Kim arrived in Hanoi to throngs of cheering, flag-waving crowds earlier today.
After a historic initial meeting in Singapore in June that produced only a vague statement about denuclearisation, analysts say the second date must deliver more concrete steps towards dismantling Pyongyang's arsenal.
The normally sleepy Vietnamese border station of Dong Dang spruced itself up for Mr Kim's arrival.
A military guard of honour in pristine white uniforms presented arms as Mr Kim strolled down the red carpet waving and grinning, surrounded by a phalanx of aides and security personnel.
Mr Kim is the first North Korean leader to visit fellow one-party state Vietnam since his grandfather Kim Il Sung in 1964.
Wearing his trademark Mao-style black suit and flanked by his troops of bodyguards, Mr Kim was ushered into a waiting Mercedes-Benz and his motorcade rolled off towards Hanoi, where armoured personnel carriers patrolled the roads amid ultra-tight security.
He was greeted in Hanoi by cheering crowds behind barriers near the colonial-era pastel yellow Hanoi Opera House before arriving at the Melia hotel where he was expected to stay this week.
Before his arrival in Hanoi, Mr Trump tweeted he was looking forward to a "very productive" second summit.
Heading over to Vietnam for my meeting with Kim Jong Un. Looking forward to a very productive Summit!— Donald J. Trump (@realDonaldTrump) February 25, 2019
The US president again dangled the carrot of economic progress for North Korea if it gives up its nuclear programme.
"With complete Denuclearization, North Korea will rapidly become an Economic Powerhouse," tweeted Mr Trump. "Without it, just more of the same."
"Chairman Kim will make a wise decision!"
Relations between the two mercurial leaders have undergone a dramatic turnaround, from flinging personal insults and threats of destruction to Mr Trump declaring he had fallen "in love" with Kim through an exchange of letters.
But many North Korea watchers dismissed the Singapore summit as a piece of political theatre that failed to produce a concrete roadmap to denuclearisation and stressed that the Hanoi meeting must deliver more.
Concrete details about the summit have been few and far between but White House spokeswoman Sarah Sanders told reporters aboard Air Force One the two leaders would dine together on Wednesday with close advisors.
Diplomatic progress since Singapore has stalled over the definition of denuclearisation, with Stephen Biegun, the US special representative for North Korea, admitting there was no "shared agreement" of what that means.
The United States has repeatedly demanded the North give up its nuclear arsenal in a final, fully verifiable way.
But Pyongyang sees denuclearisation more broadly, seeking an end to sanctions and what it sees as US threats - usually taken to include the American military presence in the South, and sometimes in the wider region.